WebCore/html/LegacyHTMLTreeBuilder.cpp
changeset 0 4f2f89ce4247
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/html/LegacyHTMLTreeBuilder.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,1786 @@
+/*
+    Copyright (C) 1997 Martin Jones (mjones@kde.org)
+              (C) 1997 Torben Weis (weis@kde.org)
+              (C) 1999,2001 Lars Knoll (knoll@kde.org)
+              (C) 2000,2001 Dirk Mueller (mueller@kde.org)
+    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
+    Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#include "config.h"
+#include "LegacyHTMLTreeBuilder.h"
+
+#include "CharacterNames.h"
+#include "CSSPropertyNames.h"
+#include "CSSValueKeywords.h"
+#include "Chrome.h"
+#include "ChromeClient.h"
+#include "Comment.h"
+#include "Console.h"
+#include "DOMWindow.h"
+#include "DocumentFragment.h"
+#include "DocumentType.h"
+#include "Frame.h"
+#include "HTMLBodyElement.h"
+#include "HTMLDocument.h"
+#include "HTMLDivElement.h"
+#include "HTMLDListElement.h"
+#include "HTMLElementFactory.h"
+#include "HTMLFormElement.h"
+#include "HTMLHeadElement.h"
+#include "HTMLHRElement.h"
+#include "HTMLHtmlElement.h"
+#include "HTMLIsIndexElement.h"
+#include "HTMLMapElement.h"
+#include "HTMLNames.h"
+#include "HTMLParserQuirks.h"
+#include "HTMLTableCellElement.h"
+#include "HTMLTableRowElement.h"
+#include "HTMLTableSectionElement.h"
+#include "LegacyHTMLDocumentParser.h"
+#include "LocalizedStrings.h"
+#include "Page.h"
+#include "Settings.h"
+#include "Text.h"
+#include "TreeDepthLimit.h"
+#include <wtf/StdLibExtras.h>
+#include <wtf/dtoa.h>
+
+namespace WebCore {
+
+using namespace HTMLNames;
+
+static const unsigned cMaxRedundantTagDepth = 20;
+static const unsigned cResidualStyleMaxDepth = 200;
+static const unsigned cResidualStyleIterationLimit = 10;
+
+
+static const int minBlockLevelTagPriority = 3;
+
+// A cap on the number of tags with priority minBlockLevelTagPriority or higher
+// allowed in m_blockStack. The cap is enforced by adding such new elements as
+// siblings instead of children once it is reached.
+static const size_t cMaxBlockDepth = 4096;
+
+
+typedef HashSet<AtomicStringImpl*> TagNameSet;
+
+template< size_t ArraySize >
+static void addTags(TagNameSet& set, QualifiedName (&names)[ArraySize])
+{
+    for (size_t x = 0; x < ArraySize; x++) {
+        const QualifiedName& name = names[x];
+        set.add(name.localName().impl());
+    }
+}
+
+struct HTMLStackElem : Noncopyable {
+    HTMLStackElem(const AtomicString& t, int lvl, Node* n, bool r, HTMLStackElem* nx)
+        : tagName(t)
+        , level(lvl)
+        , strayTableContent(false)
+        , node(n)
+        , didRefNode(r)
+        , next(nx)
+    {
+    }
+
+    void derefNode()
+    {
+        if (didRefNode)
+            node->deref();
+    }
+
+    AtomicString tagName;
+    int level;
+    bool strayTableContent;
+    Node* node;
+    bool didRefNode;
+    HTMLStackElem* next;
+};
+
+/**
+ * The parser parses tokenized input into the document, building up the
+ * document tree. If the document is well-formed, parsing it is straightforward.
+ *
+ * Unfortunately, we have to handle many HTML documents that are not well-formed,
+ * so the parser has to be tolerant about errors.
+ *
+ * We have to take care of at least the following error conditions:
+ *
+ * 1. The element being added is explicitly forbidden inside some outer tag.
+ *    In this case we should close all tags up to the one, which forbids
+ *    the element, and add it afterwards.
+ *
+ * 2. We are not allowed to add the element directly. It could be that
+ *    the person writing the document forgot some tag in between (or that the
+ *    tag in between is optional). This could be the case with the following
+ *    tags: HTML HEAD BODY TBODY TR TD LI (did I forget any?).
+ *
+ * 3. We want to add a block element inside to an inline element. Close all
+ *    inline elements up to the next higher block element.
+ *
+ * 4. If this doesn't help, close elements until we are allowed to add the
+ *    element or ignore the tag.
+ *
+ */
+
+LegacyHTMLTreeBuilder::LegacyHTMLTreeBuilder(HTMLDocument* doc, bool reportErrors)
+    : m_document(doc)
+    , m_current(doc)
+    , m_didRefCurrent(false)
+    , m_blockStack(0)
+    , m_blocksInStack(0)
+    , m_treeDepth(0)
+    , m_hasPElementInScope(NotInScope)
+    , m_inBody(false)
+    , m_haveContent(false)
+    , m_haveFrameSet(false)
+    , m_isParsingFragment(false)
+    , m_reportErrors(reportErrors)
+    , m_handlingResidualStyleAcrossBlocks(false)
+    , m_inStrayTableContent(0)
+    , m_scriptingPermission(FragmentScriptingAllowed)
+    , m_parserQuirks(m_document->page() ? m_document->page()->chrome()->client()->createHTMLParserQuirks() : 0)
+{
+}
+
+LegacyHTMLTreeBuilder::LegacyHTMLTreeBuilder(DocumentFragment* frag, FragmentScriptingPermission scriptingPermission)
+    : m_document(frag->document())
+    , m_current(frag)
+    , m_didRefCurrent(true)
+    , m_blockStack(0)
+    , m_blocksInStack(0)
+    , m_treeDepth(0)
+    , m_hasPElementInScope(NotInScope)
+    , m_inBody(true)
+    , m_haveContent(false)
+    , m_haveFrameSet(false)
+    , m_isParsingFragment(true)
+    , m_reportErrors(false)
+    , m_handlingResidualStyleAcrossBlocks(false)
+    , m_inStrayTableContent(0)
+    , m_scriptingPermission(scriptingPermission)
+    , m_parserQuirks(m_document->page() ? m_document->page()->chrome()->client()->createHTMLParserQuirks() : 0)
+{
+    if (frag)
+        frag->ref();
+}
+
+LegacyHTMLTreeBuilder::~LegacyHTMLTreeBuilder()
+{
+    freeBlock();
+    if (m_didRefCurrent)
+        m_current->deref();
+}
+
+void LegacyHTMLTreeBuilder::reset()
+{
+    ASSERT(!m_isParsingFragment);
+
+    setCurrent(m_document);
+
+    freeBlock();
+
+    m_treeDepth = 0;
+    m_inBody = false;
+    m_haveFrameSet = false;
+    m_haveContent = false;
+    m_inStrayTableContent = 0;
+
+    m_currentFormElement = 0;
+    m_currentMapElement = 0;
+    m_head = 0;
+    m_isindexElement = 0;
+
+    m_skipModeTag = nullAtom;
+    
+    if (m_parserQuirks)
+        m_parserQuirks->reset();
+}
+
+void LegacyHTMLTreeBuilder::setCurrent(Node* newCurrent) 
+{
+    bool didRefNewCurrent = newCurrent && newCurrent != m_document;
+    if (didRefNewCurrent) 
+        newCurrent->ref(); 
+    if (m_didRefCurrent) 
+        m_current->deref();
+    m_current = newCurrent;
+    m_didRefCurrent = didRefNewCurrent;
+}
+
+inline static int tagPriorityOfNode(Node* n)
+{
+    return n->isHTMLElement() ? static_cast<HTMLElement*>(n)->tagPriority() : 0;
+}
+
+inline void LegacyHTMLTreeBuilder::limitDepth(int tagPriority)
+{
+    while (m_treeDepth >= maxDOMTreeDepth)
+        popBlock(m_blockStack->tagName);
+    if (tagPriority >= minBlockLevelTagPriority) {
+        while (m_blocksInStack >= cMaxBlockDepth)
+            popBlock(m_blockStack->tagName);
+    }
+}
+
+inline bool LegacyHTMLTreeBuilder::insertNodeAfterLimitDepth(Node* n, bool flat)
+{
+    limitDepth(tagPriorityOfNode(n));
+    return insertNode(n, flat);
+}
+
+PassRefPtr<Node> LegacyHTMLTreeBuilder::parseToken(Token* t)
+{
+    if (!m_skipModeTag.isNull()) {
+        if (!t->beginTag && t->tagName == m_skipModeTag)
+            // Found the end tag for the current skip mode, so we're done skipping.
+            m_skipModeTag = nullAtom;
+        else if (m_current->localName() == t->tagName)
+            // Do not skip </iframe>.
+            // FIXME: What does that comment mean? How can it be right to parse a token without clearing m_skipModeTag?
+            ;
+        else
+            return 0;
+    }
+
+    // Apparently some sites use </br> instead of <br>. Be compatible with IE and Firefox and treat this like <br>.
+    if (t->isCloseTag(brTag) && m_document->inCompatMode()) {
+        reportError(MalformedBRError);
+        t->beginTag = true;
+    }
+
+    if (!t->beginTag) {
+        processCloseTag(t);
+        return 0;
+    }
+
+    // Ignore spaces, if we're not inside a paragraph or other inline code.
+    // Do not alter the text if it is part of a scriptTag.
+    if (t->tagName == textAtom && t->text && m_current->localName() != scriptTag) {
+        if (m_inBody && !skipMode() && m_current->localName() != styleTag &&
+            m_current->localName() != titleTag && !t->text->containsOnlyWhitespace())
+            m_haveContent = true;
+
+        // HTML5 requires text node coalescing.
+        // http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#insert-a-character
+        Node* previousChild = m_current->lastChild();
+        if (previousChild && previousChild->isTextNode()) {
+            // Only coalesce text nodes if the text node wouldn't be foster parented.
+            if (!m_current->hasTagName(htmlTag)
+                && !m_current->hasTagName(tableTag)
+                && !m_current->hasTagName(trTag)
+                && !m_current->hasTagName(theadTag)
+                && !m_current->hasTagName(tbodyTag)
+                && !m_current->hasTagName(tfootTag)
+                && !m_current->hasTagName(titleTag)) {
+                // Technically we're only supposed to merge into the previous
+                // text node if it was the last node inserted by the parser.
+                // (This was a spec modification made to make it easier for
+                // mozilla to run their parser in a thread.)
+                // In practice it does not seem to matter.
+                CharacterData* textNode = static_cast<CharacterData*>(previousChild);
+                textNode->parserAppendData(t->text);
+                return textNode;
+            }
+        }
+
+        RefPtr<Node> n;
+        String text = t->text.get();
+        unsigned charsLeft = text.length();
+        while (charsLeft) {
+            // split large blocks of text to nodes of manageable size
+            n = Text::createWithLengthLimit(m_document, text, charsLeft);
+            if (!insertNodeAfterLimitDepth(n.get(), t->selfClosingTag))
+                return 0;
+        }
+        return n;
+    }
+
+    RefPtr<Node> n = getNode(t);
+    // just to be sure, and to catch currently unimplemented stuff
+    if (!n)
+        return 0;
+
+    // set attributes
+    if (n->isHTMLElement()) {
+        HTMLElement* e = static_cast<HTMLElement*>(n.get());
+        if (m_scriptingPermission == FragmentScriptingAllowed || t->tagName != scriptTag)
+            e->setAttributeMap(t->attrs.get(), m_scriptingPermission);
+
+        // take care of optional close tags
+        if (e->endTagRequirement() == TagStatusOptional)
+            popBlock(t->tagName);
+            
+        // If the node does not have a forbidden end tag requirement, and if the broken XML self-closing
+        // syntax was used, report an error.
+        if (t->brokenXMLStyle && e->endTagRequirement() != TagStatusForbidden) {
+            if (t->tagName == scriptTag)
+                reportError(IncorrectXMLCloseScriptWarning);
+            else
+                reportError(IncorrectXMLSelfCloseError, &t->tagName);
+        }
+    }
+
+    if (!insertNodeAfterLimitDepth(n.get(), t->selfClosingTag)) {
+        // we couldn't insert the node
+
+        if (n->isElementNode()) {
+            Element* e = static_cast<Element*>(n.get());
+            e->setAttributeMap(0);
+        }
+
+        if (m_currentMapElement == n)
+            m_currentMapElement = 0;
+
+        if (m_currentFormElement == n)
+            m_currentFormElement = 0;
+
+        if (m_head == n)
+            m_head = 0;
+
+        return 0;
+    }
+    return n;
+}
+
+void LegacyHTMLTreeBuilder::parseDoctypeToken(DoctypeToken* t)
+{
+    // Ignore any doctype after the first.  Ignore doctypes in fragments.
+    if (m_document->doctype() || m_isParsingFragment || m_current != m_document)
+        return;
+
+    // Make a new doctype node and set it as our doctype.
+    m_document->legacyParserAddChild(DocumentType::create(m_document, String::adopt(t->m_name), String::adopt(t->m_publicID), String::adopt(t->m_systemID)));
+    if (t->m_forceQuirks)
+        m_document->setParseMode(Document::Compat);
+}
+
+static bool isTableSection(const Node* n)
+{
+    return n->hasTagName(tbodyTag) || n->hasTagName(tfootTag) || n->hasTagName(theadTag);
+}
+
+static bool isTablePart(const Node* n)
+{
+    return n->hasTagName(trTag) || n->hasTagName(tdTag) || n->hasTagName(thTag)
+        || isTableSection(n);
+}
+
+static bool isTableRelated(const Node* n)
+{
+    return n->hasTagName(tableTag) || isTablePart(n);
+}
+
+static bool isScopingTag(const AtomicString& tagName)
+{
+    return tagName == appletTag || tagName == captionTag || tagName == tdTag
+        || tagName == thTag || tagName == buttonTag || tagName == marqueeTag
+        || tagName == objectTag || tagName == tableTag || tagName == htmlTag;
+}
+
+bool LegacyHTMLTreeBuilder::insertNode(Node* n, bool flat)
+{
+    RefPtr<Node> protectNode(n);
+
+    const AtomicString& localName = n->localName();
+    
+    // <table> is never allowed inside stray table content.  Always pop out of the stray table content
+    // and close up the first table, and then start the second table as a sibling.
+    if (m_inStrayTableContent && localName == tableTag)
+        popBlock(tableTag);
+
+    if (m_parserQuirks && !m_parserQuirks->shouldInsertNode(m_current, n))
+        return false;
+
+    int tagPriority = tagPriorityOfNode(n);
+
+    // let's be stupid and just try to insert it.
+    // this should work if the document is well-formed
+    Node* newNode = m_current->legacyParserAddChild(n);
+    if (!newNode)
+        return handleError(n, flat, localName, tagPriority); // Try to handle the error.
+
+    // don't push elements without end tags (e.g., <img>) on the stack
+    bool parentAttached = m_current->attached();
+    if (tagPriority > 0 && !flat) {
+        if (newNode == m_current) {
+            // This case should only be hit when a demoted <form> is placed inside a table.
+            ASSERT(localName == formTag);
+            reportError(FormInsideTablePartError, &m_current->localName());
+            HTMLFormElement* form = static_cast<HTMLFormElement*>(n);
+            form->setDemoted(true);
+        } else {
+            // The pushBlock function transfers ownership of current to the block stack
+            // so we're guaranteed that m_didRefCurrent is false. The code below is an
+            // optimized version of setCurrent that takes advantage of that fact and also
+            // assumes that newNode is neither 0 nor a pointer to the document.
+            pushBlock(localName, tagPriority);
+            newNode->beginParsingChildren();
+            ASSERT(!m_didRefCurrent);
+            newNode->ref(); 
+            m_current = newNode;
+            m_didRefCurrent = true;
+        }
+        if (parentAttached && !n->attached() && !m_isParsingFragment)
+            n->attach();
+    } else {
+        if (parentAttached && !n->attached() && !m_isParsingFragment)
+            n->attach();
+        n->finishParsingChildren();
+    }
+
+    if (localName == htmlTag && m_document->frame() && !m_isParsingFragment)
+        m_document->frame()->loader()->dispatchDocumentElementAvailable();
+
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::handleError(Node* n, bool flat, const AtomicString& localName, int tagPriority)
+{
+    // Error handling code.  This is just ad hoc handling of specific parent/child combinations.
+    bool handled = false;
+
+    // 1. Check out the element's tag name to decide how to deal with errors.
+    if (n->isHTMLElement()) {
+        HTMLElement* h = static_cast<HTMLElement*>(n);
+        if (h->hasLocalName(trTag) || h->hasLocalName(thTag) || h->hasLocalName(tdTag)) {
+            if (m_inStrayTableContent && !isTableRelated(m_current)) {
+                reportError(MisplacedTablePartError, &localName, &m_current->localName());
+                // pop out to the nearest enclosing table-related tag.
+                while (m_blockStack && !isTableRelated(m_current))
+                    popOneBlock();
+                return insertNode(n);
+            }
+        } else if (h->hasLocalName(headTag)) {
+            if (!m_current->isDocumentNode() && !m_current->hasTagName(htmlTag)) {
+                reportError(MisplacedHeadError);
+                return false;
+            }
+        } else if (h->hasLocalName(metaTag) || h->hasLocalName(linkTag) || h->hasLocalName(baseTag)) {
+            bool createdHead = false;
+            if (!m_head) {
+                createHead();
+                createdHead = true;
+            }
+            if (m_head) {
+                if (!createdHead)
+                    reportError(MisplacedHeadContentError, &localName, &m_current->localName());
+                if (m_head->legacyParserAddChild(n)) {
+                    if (!n->attached() && !m_isParsingFragment)
+                        n->attach();
+                    return true;
+                }
+                return false;
+            }
+        } else if (h->hasLocalName(htmlTag)) {
+            if (!m_current->isDocumentNode() ) {
+                if (m_document->documentElement() && m_document->documentElement()->hasTagName(htmlTag) && !m_isParsingFragment) {
+                    reportError(RedundantHTMLBodyError, &localName);
+                    // we have another <HTML> element.... apply attributes to existing one
+                    // make sure we don't overwrite already existing attributes
+                    NamedNodeMap* map = static_cast<Element*>(n)->attributes(true);
+                    Element* existingHTML = static_cast<Element*>(m_document->documentElement());
+                    NamedNodeMap* bmap = existingHTML->attributes(false);
+                    for (unsigned l = 0; map && l < map->length(); ++l) {
+                        Attribute* it = map->attributeItem(l);
+                        if (!bmap->getAttributeItem(it->name()))
+                            existingHTML->setAttribute(it->name(), it->value());
+                    }
+                }
+                return false;
+            }
+        } else if (h->hasLocalName(titleTag) || h->hasLocalName(styleTag) || h->hasLocalName(scriptTag)) {
+            bool createdHead = false;
+            if (!m_head) {
+                createHead();
+                createdHead = true;
+            }
+            if (m_head) {
+                Node* newNode = m_head->legacyParserAddChild(n);
+                if (!newNode) {
+                    setSkipMode(h->tagQName());
+                    return false;
+                }
+                
+                if (!createdHead)
+                    reportError(MisplacedHeadContentError, &localName, &m_current->localName());
+                
+                pushBlock(localName, tagPriority);
+                newNode->beginParsingChildren();
+                setCurrent(newNode);
+                if (!n->attached() && !m_isParsingFragment)
+                    n->attach();
+                return true;
+            }
+            if (m_inBody) {
+                setSkipMode(h->tagQName());
+                return false;
+            }
+        } else if (h->hasLocalName(bodyTag)) {
+            if (m_inBody && m_document->body() && !m_isParsingFragment) {
+                // we have another <BODY> element.... apply attributes to existing one
+                // make sure we don't overwrite already existing attributes
+                // some sites use <body bgcolor=rightcolor>...<body bgcolor=wrongcolor>
+                reportError(RedundantHTMLBodyError, &localName);
+                NamedNodeMap* map = static_cast<Element*>(n)->attributes(true);
+                Element* existingBody = m_document->body();
+                NamedNodeMap* bmap = existingBody->attributes(false);
+                for (unsigned l = 0; map && l < map->length(); ++l) {
+                    Attribute* it = map->attributeItem(l);
+                    if (!bmap->getAttributeItem(it->name()))
+                        existingBody->setAttribute(it->name(), it->value());
+                }
+                return false;
+            } else if (!m_current->isDocumentNode())
+                return false;
+        } else if (h->hasLocalName(areaTag)) {
+            if (m_currentMapElement) {
+                reportError(MisplacedAreaError, &m_current->localName());
+                m_currentMapElement->legacyParserAddChild(n);
+                if (!n->attached() && !m_isParsingFragment)
+                    n->attach();
+                handled = true;
+                return true;
+            }
+            return false;
+        } else if (h->hasLocalName(colgroupTag) || h->hasLocalName(captionTag)) {
+            if (isTableRelated(m_current)) {
+                while (m_blockStack && isTablePart(m_current))
+                    popOneBlock();
+                return insertNode(n);
+            }
+        }
+    } else if (n->isCommentNode() && !m_head)
+        return false;
+
+    // 2. Next we examine our currently active element to do some further error handling.
+    if (m_current->isHTMLElement()) {
+        HTMLElement* h = static_cast<HTMLElement*>(m_current);
+        const AtomicString& currentTagName = h->localName();
+        if (h->hasLocalName(htmlTag)) {
+            HTMLElement* elt = n->isHTMLElement() ? static_cast<HTMLElement*>(n) : 0;
+            if (elt && (elt->hasLocalName(scriptTag) || elt->hasLocalName(styleTag) ||
+                elt->hasLocalName(metaTag) || elt->hasLocalName(linkTag) ||
+                elt->hasLocalName(objectTag) || elt->hasLocalName(embedTag) ||
+                elt->hasLocalName(titleTag) || elt->hasLocalName(isindexTag) ||
+                elt->hasLocalName(baseTag))) {
+                if (!m_head) {
+                    m_head = HTMLHeadElement::create(m_document);
+                    insertNode(m_head.get());
+                    handled = true;
+                }
+            } else {
+                if (n->isTextNode()) {
+                    Text* t = static_cast<Text*>(n);
+                    if (t->containsOnlyWhitespace()) {
+                        if (m_head && !m_inBody) {
+                            // We're between </head> and <body>.  According to
+                            // the HTML5 parsing algorithm, we're supposed to
+                            // insert whitespace text nodes into the HTML element.
+                            ExceptionCode ec;
+                            m_current->appendChild(n, ec);
+                            return true;
+                        }
+                        return false;
+                    }
+                }
+                if (!m_haveFrameSet) {
+                    // Ensure that head exists.
+                    // But not for older versions of Mail, where the implicit <head> isn't expected - <rdar://problem/6863795>
+                    if (!m_isParsingFragment && shouldCreateImplicitHead(m_document))
+                        createHead();
+
+                    popBlock(headTag);
+                    startBody();
+                    insertNode(HTMLBodyElement::create(m_document).get());
+                    handled = true;
+                } else
+                    reportError(MisplacedFramesetContentError, &localName);
+            }
+        } else if (h->hasLocalName(headTag)) {
+            if (n->hasTagName(htmlTag))
+                return false;
+            else {
+                // This means the body starts here...
+                if (!m_haveFrameSet) {
+                    ASSERT(currentTagName == headTag);
+                    popBlock(currentTagName);
+                    startBody();
+                    insertNode(HTMLBodyElement::create(m_document).get());
+                    handled = true;
+                } else
+                    reportError(MisplacedFramesetContentError, &localName);
+            }
+        } else if (h->hasLocalName(addressTag) || h->hasLocalName(fontTag)
+                   || h->hasLocalName(styleTag) || h->hasLocalName(titleTag)) {
+            reportError(MisplacedContentRetryError, &localName, &currentTagName);
+            popBlock(currentTagName);
+            handled = true;
+        } else if (h->hasLocalName(captionTag)) {
+            // Illegal content in a caption. Close the caption and try again.
+            reportError(MisplacedCaptionContentError, &localName);
+            popBlock(currentTagName);
+            if (isTablePart(n))
+                return insertNode(n, flat);
+        } else if (h->hasLocalName(tableTag) || h->hasLocalName(trTag) || isTableSection(h)) {
+            if (n->hasTagName(tableTag)) {
+                reportError(MisplacedTableError, &currentTagName);
+                if (m_isParsingFragment && !h->hasLocalName(tableTag))
+                    // fragment may contain table parts without <table> ancestor, pop them one by one
+                    popBlock(h->localName());
+                popBlock(localName); // end the table
+                handled = true;      // ...and start a new one
+            } else {
+                ExceptionCode ec = 0;
+                Node* node = m_current;
+                Node* parent = node->parentNode();
+                // A script may have removed the current node's parent from the DOM
+                // http://bugs.webkit.org/show_bug.cgi?id=7137
+                // FIXME: we should do real recovery here and re-parent with the correct node.
+                if (!parent)
+                    return false;
+                Node* grandparent = parent->parentNode();
+
+                if (n->isTextNode() ||
+                    (h->hasLocalName(trTag) &&
+                     isTableSection(parent) && grandparent && grandparent->hasTagName(tableTag)) ||
+                     ((!n->hasTagName(tdTag) && !n->hasTagName(thTag) &&
+                       !n->hasTagName(formTag) && !n->hasTagName(scriptTag)) && isTableSection(node) &&
+                     parent->hasTagName(tableTag))) {
+                    node = (node->hasTagName(tableTag)) ? node :
+                            ((node->hasTagName(trTag)) ? grandparent : parent);
+                    // This can happen with fragments
+                    if (!node)
+                        return false;
+                    Node* parent = node->parentNode();
+                    if (!parent)
+                        return false;
+                    parent->insertBefore(n, node, ec);
+                    if (!ec) {
+                        reportError(StrayTableContentError, &localName, &currentTagName);
+                        if (n->isHTMLElement() && tagPriority > 0 && 
+                            !flat && static_cast<HTMLElement*>(n)->endTagRequirement() != TagStatusForbidden)
+                        {
+                            pushBlock(localName, tagPriority);
+                            n->beginParsingChildren();
+                            setCurrent(n);
+                            m_inStrayTableContent++;
+                            m_blockStack->strayTableContent = true;
+                        }
+                        return true;
+                    }
+                }
+
+                if (!ec) {
+                    if (m_current->hasTagName(trTag)) {
+                        reportError(TablePartRequiredError, &localName, &tdTag.localName());
+                        insertNode(HTMLTableCellElement::create(tdTag, m_document).get());
+                    } else if (m_current->hasTagName(tableTag)) {
+                        // Don't report an error in this case, since making a <tbody> happens all the time when you have <table><tr>,
+                        // and it isn't really a parse error per se.
+                        insertNode(HTMLTableSectionElement::create(tbodyTag, m_document).get());
+                    } else {
+                        reportError(TablePartRequiredError, &localName, &trTag.localName());
+                        insertNode(HTMLTableRowElement::create(m_document).get());
+                    }
+                    handled = true;
+                }
+            }
+        } else if (h->hasLocalName(objectTag)) {
+            reportError(MisplacedContentRetryError, &localName, &currentTagName);
+            popBlock(objectTag);
+            handled = true;
+        } else if (h->hasLocalName(pTag) || isHeadingTag(currentTagName)) {
+            if (!isInline(n)) {
+                popBlock(currentTagName);
+                handled = true;
+            }
+        } else if (h->hasLocalName(optionTag) || h->hasLocalName(optgroupTag)) {
+            if (localName == optgroupTag) {
+                popBlock(currentTagName);
+                handled = true;
+            } else if (localName == selectTag) {
+                // IE treats a nested select as </select>. Let's do the same
+                popBlock(localName);
+            }
+        } else if (h->hasLocalName(selectTag)) {
+            if (localName == inputTag || localName == textareaTag) {
+                reportError(MisplacedContentRetryError, &localName, &currentTagName);
+                popBlock(currentTagName);
+                handled = true;
+            }
+        } else if (h->hasLocalName(colgroupTag)) {
+            popBlock(currentTagName);
+            handled = true;
+        } else if (!h->hasLocalName(bodyTag)) {
+            if (isInline(m_current)) {
+                popInlineBlocks();
+                handled = true;
+            }
+        }
+    } else if (m_current->isDocumentNode()) {
+        if (n->isTextNode()) {
+            Text* t = static_cast<Text*>(n);
+            if (t->containsOnlyWhitespace())
+                return false;
+        }
+
+        if (!m_document->documentElement()) {
+            insertNode(HTMLHtmlElement::create(m_document).get());
+            handled = true;
+        }
+    }
+
+    // 3. If we couldn't handle the error, just return false and attempt to error-correct again.
+    if (!handled) {
+        reportError(IgnoredContentError, &localName, &m_current->localName());
+        return false;
+    }
+    return insertNode(n);
+}
+
+typedef bool (LegacyHTMLTreeBuilder::*CreateErrorCheckFunc)(Token* t, RefPtr<Node>&);
+typedef HashMap<AtomicStringImpl*, CreateErrorCheckFunc> FunctionMap;
+
+bool LegacyHTMLTreeBuilder::textCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    result = Text::create(m_document, t->text.get());
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::commentCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    result = Comment::create(m_document, t->text.get());
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::headCreateErrorCheck(Token*, RefPtr<Node>& result)
+{
+    if (!m_head || m_current->localName() == htmlTag) {
+        m_head = HTMLHeadElement::create(m_document);
+        result = m_head;
+    } else
+        reportError(MisplacedHeadError);
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::bodyCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    // body no longer allowed if we have a frameset
+    if (m_haveFrameSet)
+        return false;
+    
+    // Ensure that head exists (unless parsing a fragment).
+    // But not for older versions of Mail, where the implicit <head> isn't expected - <rdar://problem/6863795>
+    if (!m_isParsingFragment && shouldCreateImplicitHead(m_document))
+        createHead();
+    
+    popBlock(headTag);
+    startBody();
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::framesetCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    popBlock(headTag);
+    if (m_inBody && !m_haveFrameSet && !m_haveContent) {
+        popBlock(bodyTag);
+        // ### actually for IE document.body returns the now hidden "body" element
+        // we can't implement that behaviour now because it could cause too many
+        // regressions and the headaches are not worth the work as long as there is
+        // no site actually relying on that detail (Dirk)
+        if (m_document->body() && !m_isParsingFragment)
+            m_document->body()->setAttribute(styleAttr, "display:none");
+        m_inBody = false;
+    }
+    if ((m_haveContent || m_haveFrameSet) && m_current->localName() == htmlTag)
+        return false;
+    m_haveFrameSet = true;
+    startBody();
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::formCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    // Only create a new form if we're not already inside one.
+    // This is consistent with other browsers' behavior.
+    if (!m_currentFormElement) {
+        m_currentFormElement = HTMLFormElement::create(m_document);
+        result = m_currentFormElement;
+        pCloserCreateErrorCheck(t, result);
+    }
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::isindexCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    RefPtr<Node> n = handleIsindex(t);
+    if (!m_inBody)
+        m_isindexElement = n.release();
+    else {
+        t->selfClosingTag = true;
+        result = n.release();
+    }
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::selectCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::ddCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    pCloserCreateErrorCheck(t, result);
+    popBlock(dtTag);
+    popBlock(ddTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::dtCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    pCloserCreateErrorCheck(t, result);
+    popBlock(ddTag);
+    popBlock(dtTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::rpCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    popBlock(rpTag);
+    popBlock(rtTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::rtCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    popBlock(rpTag);
+    popBlock(rtTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::nestedCreateErrorCheck(Token* t, RefPtr<Node>&)
+{
+    popBlock(t->tagName);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::nestedPCloserCreateErrorCheck(Token* t, RefPtr<Node>& result)
+{
+    pCloserCreateErrorCheck(t, result);
+    popBlock(t->tagName);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::nestedStyleCreateErrorCheck(Token* t, RefPtr<Node>&)
+{
+    return allowNestedRedundantTag(t->tagName);
+}
+
+bool LegacyHTMLTreeBuilder::colCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    if (!m_current->hasTagName(tableTag))
+        return true;
+    RefPtr<Element> implicitColgroup = HTMLElementFactory::createHTMLElement(colgroupTag, m_document, 0, true);
+    insertNode(implicitColgroup.get());
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::tableCellCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    popBlock(tdTag);
+    popBlock(thTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::tableSectionCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    popBlock(theadTag);
+    popBlock(tbodyTag);
+    popBlock(tfootTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::noembedCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    setSkipMode(noembedTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::noframesCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    setSkipMode(noframesTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::noscriptCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    if (!m_isParsingFragment) {
+        Frame* frame = m_document->frame();
+        if (frame && frame->script()->canExecuteScripts(NotAboutToExecuteScript))
+            setSkipMode(noscriptTag);
+    }
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::pCloserCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    if (hasPElementInScope())
+        popBlock(pTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::pCloserStrictCreateErrorCheck(Token*, RefPtr<Node>&)
+{
+    if (m_document->inCompatMode())
+        return true;
+    if (hasPElementInScope())
+        popBlock(pTag);
+    return true;
+}
+
+bool LegacyHTMLTreeBuilder::mapCreateErrorCheck(Token*, RefPtr<Node>& result)
+{
+    m_currentMapElement = HTMLMapElement::create(m_document);
+    result = m_currentMapElement;
+    return false;
+}
+
+static void mapTagToFunc(FunctionMap& map, const QualifiedName& tag, CreateErrorCheckFunc func)
+{
+    map.set(tag.localName().impl(), func);
+}
+
+template< size_t ArraySize >
+static void mapTagsToFunc(FunctionMap& map, QualifiedName (&names)[ArraySize], CreateErrorCheckFunc func)
+{
+    for (size_t x = 0; x < ArraySize; x++) {
+        const QualifiedName& name = names[x];
+        mapTagToFunc(map, name, func);
+    }
+}
+
+PassRefPtr<Node> LegacyHTMLTreeBuilder::getNode(Token* t)
+{
+    // Init our error handling table.
+    DEFINE_STATIC_LOCAL(FunctionMap, gFunctionMap, ());
+    if (gFunctionMap.isEmpty()) {
+        QualifiedName nestedCreateErrorTags[] = { aTag, buttonTag, nobrTag, trTag };
+        mapTagsToFunc(gFunctionMap, nestedCreateErrorTags, &LegacyHTMLTreeBuilder::nestedCreateErrorCheck);
+
+        QualifiedName nestedStyleCreateErrorTags[] = { bTag, bigTag, iTag, markTag, sTag, smallTag, strikeTag, ttTag, uTag };
+        mapTagsToFunc(gFunctionMap, nestedStyleCreateErrorTags, &LegacyHTMLTreeBuilder::nestedStyleCreateErrorCheck);
+
+        QualifiedName pCloserCreateErrorTags[] = { addressTag, articleTag,
+            asideTag, blockquoteTag, centerTag, dirTag, divTag, dlTag,
+            fieldsetTag, footerTag, h1Tag, h2Tag, h3Tag, h4Tag, h5Tag, h6Tag,
+            headerTag, hgroupTag, hrTag, listingTag, menuTag, navTag, olTag,
+            pTag, plaintextTag, preTag, sectionTag, ulTag };
+        mapTagsToFunc(gFunctionMap, pCloserCreateErrorTags, &LegacyHTMLTreeBuilder::pCloserCreateErrorCheck);
+
+        mapTagToFunc(gFunctionMap, bodyTag, &LegacyHTMLTreeBuilder::bodyCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, colTag, &LegacyHTMLTreeBuilder::colCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, ddTag, &LegacyHTMLTreeBuilder::ddCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, dtTag, &LegacyHTMLTreeBuilder::dtCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, formTag, &LegacyHTMLTreeBuilder::formCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, framesetTag, &LegacyHTMLTreeBuilder::framesetCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, headTag, &LegacyHTMLTreeBuilder::headCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, isindexTag, &LegacyHTMLTreeBuilder::isindexCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, mapTag, &LegacyHTMLTreeBuilder::mapCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, liTag, &LegacyHTMLTreeBuilder::nestedPCloserCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, noembedTag, &LegacyHTMLTreeBuilder::noembedCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, noframesTag, &LegacyHTMLTreeBuilder::noframesCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, noscriptTag, &LegacyHTMLTreeBuilder::noscriptCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, tableTag, &LegacyHTMLTreeBuilder::pCloserStrictCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, rpTag, &LegacyHTMLTreeBuilder::rpCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, rtTag, &LegacyHTMLTreeBuilder::rtCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, selectTag, &LegacyHTMLTreeBuilder::selectCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, tdTag, &LegacyHTMLTreeBuilder::tableCellCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, thTag, &LegacyHTMLTreeBuilder::tableCellCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, tbodyTag, &LegacyHTMLTreeBuilder::tableSectionCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, tfootTag, &LegacyHTMLTreeBuilder::tableSectionCreateErrorCheck);
+        mapTagToFunc(gFunctionMap, theadTag, &LegacyHTMLTreeBuilder::tableSectionCreateErrorCheck);
+
+        gFunctionMap.set(commentAtom.impl(), &LegacyHTMLTreeBuilder::commentCreateErrorCheck);
+        gFunctionMap.set(textAtom.impl(), &LegacyHTMLTreeBuilder::textCreateErrorCheck);
+    }
+
+    bool proceed = true;
+    RefPtr<Node> result;
+    if (CreateErrorCheckFunc errorCheckFunc = gFunctionMap.get(t->tagName.impl()))
+        proceed = (this->*errorCheckFunc)(t, result);
+    if (proceed)
+        result = HTMLElementFactory::createHTMLElement(QualifiedName(nullAtom, t->tagName, xhtmlNamespaceURI), m_document, m_currentFormElement.get());
+    return result.release();
+}
+
+bool LegacyHTMLTreeBuilder::allowNestedRedundantTag(const AtomicString& tagName)
+{
+    // www.liceo.edu.mx is an example of a site that achieves a level of nesting of
+    // about 1500 tags, all from a bunch of <b>s.  We will only allow at most 20
+    // nested tags of the same type before just ignoring them all together.
+    unsigned i = 0;
+    for (HTMLStackElem* curr = m_blockStack;
+         i < cMaxRedundantTagDepth && curr && curr->tagName == tagName;
+         curr = curr->next, i++) { }
+    return i != cMaxRedundantTagDepth;
+}
+
+void LegacyHTMLTreeBuilder::processCloseTag(Token* t)
+{
+    // Support for really broken html.
+    // we never close the body tag, since some stupid web pages close it before the actual end of the doc.
+    // let's rely on the end() call to close things.
+    if (t->tagName == htmlTag || t->tagName == bodyTag || t->tagName == commentAtom)
+        return;
+    
+    bool checkForCloseTagErrors = true;
+    if (t->tagName == formTag && m_currentFormElement) {
+        m_currentFormElement = 0;
+        checkForCloseTagErrors = false;
+    } else if (t->tagName == mapTag)
+        m_currentMapElement = 0;
+    else if (t->tagName == pTag)
+        checkForCloseTagErrors = false;
+        
+    HTMLStackElem* oldElem = m_blockStack;
+    popBlock(t->tagName, checkForCloseTagErrors);
+    if (oldElem == m_blockStack && t->tagName == pTag) {
+        // We encountered a stray </p>.  Amazingly Gecko, WinIE, and MacIE all treat
+        // this as a valid break, i.e., <p></p>.  So go ahead and make the empty
+        // paragraph.
+        t->beginTag = true;
+        parseToken(t);
+        popBlock(t->tagName);
+        reportError(StrayParagraphCloseError);
+    }
+}
+
+bool LegacyHTMLTreeBuilder::isHeadingTag(const AtomicString& tagName)
+{
+    DEFINE_STATIC_LOCAL(TagNameSet, headingTags, ());
+    if (headingTags.isEmpty()) {
+        QualifiedName tagNames[] = { h1Tag, h2Tag, h3Tag, h4Tag, h5Tag, h6Tag };
+        addTags(headingTags, tagNames);
+    }
+    return headingTags.contains(tagName.impl());
+}
+
+bool LegacyHTMLTreeBuilder::isInline(Node* node) const
+{
+    if (node->isTextNode())
+        return true;
+
+    if (node->isHTMLElement()) {
+        HTMLElement* e = static_cast<HTMLElement*>(node);
+        if (e->hasLocalName(aTag) || e->hasLocalName(fontTag) || e->hasLocalName(ttTag) ||
+            e->hasLocalName(uTag) || e->hasLocalName(bTag) || e->hasLocalName(iTag) ||
+            e->hasLocalName(sTag) || e->hasLocalName(strikeTag) || e->hasLocalName(bigTag) ||
+            e->hasLocalName(smallTag) || e->hasLocalName(emTag) || e->hasLocalName(strongTag) ||
+            e->hasLocalName(dfnTag) || e->hasLocalName(codeTag) || e->hasLocalName(sampTag) ||
+            e->hasLocalName(kbdTag) || e->hasLocalName(varTag) || e->hasLocalName(citeTag) ||
+            e->hasLocalName(abbrTag) || e->hasLocalName(acronymTag) || e->hasLocalName(subTag) ||
+            e->hasLocalName(supTag) || e->hasLocalName(spanTag) || e->hasLocalName(nobrTag) ||
+            e->hasLocalName(noframesTag) || e->hasLocalName(nolayerTag) ||
+            e->hasLocalName(noembedTag) || e->hasLocalName(markTag))
+            return true;
+#if !ENABLE(XHTMLMP)
+        if (e->hasLocalName(noscriptTag) && !m_isParsingFragment) {
+            Frame* frame = m_document->frame();
+            if (frame && frame->script()->canExecuteScripts(NotAboutToExecuteScript))
+                return true;
+        }
+#endif
+    }
+    
+    return false;
+}
+
+bool LegacyHTMLTreeBuilder::isResidualStyleTag(const AtomicString& tagName)
+{
+    DEFINE_STATIC_LOCAL(HashSet<AtomicStringImpl*>, residualStyleTags, ());
+    if (residualStyleTags.isEmpty()) {
+        QualifiedName tagNames[] = { aTag, fontTag, ttTag, uTag, bTag, iTag,
+            sTag, strikeTag, bigTag, smallTag, emTag, strongTag, dfnTag,
+            codeTag, sampTag, kbdTag, varTag, nobrTag, markTag };
+        addTags(residualStyleTags, tagNames);
+    }
+    return residualStyleTags.contains(tagName.impl());
+}
+
+bool LegacyHTMLTreeBuilder::isAffectedByResidualStyle(const AtomicString& tagName)
+{
+    DEFINE_STATIC_LOCAL(HashSet<AtomicStringImpl*>, unaffectedTags, ());
+    if (unaffectedTags.isEmpty()) {
+        QualifiedName tagNames[] = { bodyTag, tableTag, theadTag, tbodyTag,
+            tfootTag, trTag, thTag, tdTag, captionTag, colgroupTag, colTag,
+            optionTag, optgroupTag, selectTag, objectTag, datagridTag, datalistTag };
+        addTags(unaffectedTags, tagNames);
+    }
+    return !unaffectedTags.contains(tagName.impl());
+}
+
+void LegacyHTMLTreeBuilder::handleResidualStyleCloseTagAcrossBlocks(HTMLStackElem* elem)
+{
+    HTMLStackElem* maxElem = 0;
+    bool finished = false;
+    bool strayTableContent = elem->strayTableContent;
+
+    unsigned iterationCount = 0;
+
+    m_handlingResidualStyleAcrossBlocks = true;
+    while (!finished && (iterationCount++ < cResidualStyleIterationLimit)) {
+        // Find the outermost element that crosses over to a higher level. If there exists another higher-level
+        // element, we will do another pass, until we have corrected the innermost one.
+        ExceptionCode ec = 0;
+        HTMLStackElem* curr = m_blockStack;
+        HTMLStackElem* prev = 0;
+        HTMLStackElem* prevMaxElem = 0;
+        maxElem = 0;
+        finished = true;
+        while (curr && curr != elem) {
+            if (curr->level > elem->level) {
+                if (!isAffectedByResidualStyle(curr->tagName))
+                    return;
+                if (maxElem)
+                    // We will need another pass.
+                    finished = false;
+                maxElem = curr;
+                prevMaxElem = prev;
+            }
+
+            prev = curr;
+            curr = curr->next;
+        }
+
+        if (!curr || !maxElem)
+            return;
+
+        Node* residualElem = prev->node;
+        Node* blockElem = prevMaxElem ? prevMaxElem->node : m_current;
+        Node* parentElem = elem->node;
+
+        // Check to see if the reparenting that is going to occur is allowed according to the DOM.
+        // FIXME: We should either always allow it or perform an additional fixup instead of
+        // just bailing here.
+        // Example: <p><font><center>blah</font></center></p> isn't doing a fixup right now.
+        if (!parentElem->childAllowed(blockElem))
+            return;
+
+        m_hasPElementInScope = Unknown;
+
+        if (maxElem->node->parentNode() != elem->node) {
+            // Walk the stack and remove any elements that aren't residual style tags.  These
+            // are basically just being closed up.  Example:
+            // <font><span>Moo<p>Goo</font></p>.
+            // In the above example, the <span> doesn't need to be reopened.  It can just close.
+            HTMLStackElem* currElem = maxElem->next;
+            HTMLStackElem* prevElem = maxElem;
+            while (currElem != elem) {
+                HTMLStackElem* nextElem = currElem->next;
+                if (!isResidualStyleTag(currElem->tagName)) {
+                    prevElem->next = nextElem;
+                    prevElem->derefNode();
+                    prevElem->node = currElem->node;
+                    prevElem->didRefNode = currElem->didRefNode;
+                    delete currElem;
+                    m_treeDepth--;
+                } else
+                    prevElem = currElem;
+                currElem = nextElem;
+            }
+
+            // We have to reopen residual tags in between maxElem and elem.  An example of this case is:
+            // <font><i>Moo<p>Foo</font>.
+            // In this case, we need to transform the part before the <p> into:
+            // <font><i>Moo</i></font><i>
+            // so that the <i> will remain open.  This involves the modification of elements
+            // in the block stack.
+            // This will also affect how we ultimately reparent the block, since we want it to end up
+            // under the reopened residual tags (e.g., the <i> in the above example.)
+            RefPtr<Node> prevNode = 0;
+            currElem = maxElem;
+            while (currElem->node != residualElem) {
+                if (isResidualStyleTag(currElem->node->localName())) {
+                    // Create a clone of this element.
+                    // We call releaseRef to get a raw pointer since we plan to hand over ownership to currElem.
+                    Node* currNode = currElem->node->cloneNode(false).releaseRef();
+                    reportError(ResidualStyleError, &currNode->localName());
+    
+                    // Change the stack element's node to point to the clone.
+                    // The stack element adopts the reference we obtained above by calling release().
+                    currElem->derefNode();
+                    currElem->node = currNode;
+                    currElem->didRefNode = true;
+
+                    // Attach the previous node as a child of this new node.
+                    if (prevNode)
+                        currNode->appendChild(prevNode, ec);
+                    else // The new parent for the block element is going to be the innermost clone.
+                        parentElem = currNode;  // FIXME: We shifted parentElem to be a residual inline.  We never checked to see if blockElem could be legally placed inside the inline though.
+
+                    prevNode = currNode;
+                }
+
+                currElem = currElem->next;
+            }
+
+            // Now append the chain of new residual style elements if one exists.
+            if (prevNode)
+                elem->node->appendChild(prevNode, ec);  // FIXME: This append can result in weird stuff happening, like an inline chain being put into a table section.
+        }
+
+        // Check if the block is still in the tree. If it isn't, then we don't
+        // want to remove it from its parent (that would crash) or insert it into
+        // a new parent later. See http://bugs.webkit.org/show_bug.cgi?id=6778
+        bool isBlockStillInTree = blockElem->parentNode();
+
+        // We need to make a clone of |residualElem| and place it just inside |blockElem|.
+        // All content of |blockElem| is reparented to be under this clone.  We then
+        // reparent |blockElem| using real DOM calls so that attachment/detachment will
+        // be performed to fix up the rendering tree.
+        // So for this example: <b>...<p>Foo</b>Goo</p>
+        // The end result will be: <b>...</b><p><b>Foo</b>Goo</p>
+        //
+        // Step 1: Remove |blockElem| from its parent, doing a batch detach of all the kids.
+        if (isBlockStillInTree)
+            blockElem->parentNode()->removeChild(blockElem, ec);
+
+        Node* newNodePtr = 0;
+        if (blockElem->firstChild()) {
+            // Step 2: Clone |residualElem|.
+            RefPtr<Node> newNode = residualElem->cloneNode(false); // Shallow clone. We don't pick up the same kids.
+            newNodePtr = newNode.get();
+            reportError(ResidualStyleError, &newNode->localName());
+
+            // Step 3: Place |blockElem|'s children under |newNode|.  Remove all of the children of |blockElem|
+            // before we've put |newElem| into the document.  That way we'll only do one attachment of all
+            // the new content (instead of a bunch of individual attachments).
+            Node* currNode = blockElem->firstChild();
+            while (currNode) {
+                Node* nextNode = currNode->nextSibling();
+                newNode->appendChild(currNode, ec);
+                currNode = nextNode;
+            }
+
+            // Step 4: Place |newNode| under |blockElem|.  |blockElem| is still out of the document, so no
+            // attachment can occur yet.
+            blockElem->appendChild(newNode.release(), ec);
+        } else
+            finished = true;
+
+        // Step 5: Reparent |blockElem|.  Now the full attachment of the fixed up tree takes place.
+        if (isBlockStillInTree)
+            parentElem->appendChild(blockElem, ec);
+
+        // Step 6: Pull |elem| out of the stack, since it is no longer enclosing us.  Also update
+        // the node associated with the previous stack element so that when it gets popped,
+        // it doesn't make the residual element the next current node.
+        HTMLStackElem* currElem = maxElem;
+        HTMLStackElem* prevElem = 0;
+        while (currElem != elem) {
+            prevElem = currElem;
+            currElem = currElem->next;
+        }
+        prevElem->next = elem->next;
+        prevElem->derefNode();
+        prevElem->node = elem->node;
+        prevElem->didRefNode = elem->didRefNode;
+        m_treeDepth--;
+        if (!finished) {
+            // Repurpose |elem| to represent |newNode| and insert it at the appropriate position
+            // in the stack. We do not do this for the innermost block, because in that case the new
+            // node is effectively no longer open.
+            elem->next = maxElem;
+            elem->node = prevMaxElem->node;
+            elem->didRefNode = prevMaxElem->didRefNode;
+            elem->strayTableContent = false;
+            prevMaxElem->next = elem;
+            ASSERT(newNodePtr);
+            prevMaxElem->node = newNodePtr;
+            newNodePtr->ref();
+            prevMaxElem->didRefNode = true;
+            m_treeDepth++;
+        } else
+            delete elem;
+    }
+
+    // FIXME: If we ever make a case like this work:
+    // <table><b><i><form></b></form></i></table>
+    // Then this check will be too simplistic.  Right now the <i><form> chain will end up inside the <tbody>, which is pretty crazy.
+    if (strayTableContent)
+        m_inStrayTableContent--;
+
+    // Step 7: Reopen intermediate inlines, e.g., <b><p><i>Foo</b>Goo</p>.
+    // In the above example, Goo should stay italic.
+    // We cap the number of tags we're willing to reopen based off cResidualStyleMaxDepth.
+    
+    HTMLStackElem* curr = m_blockStack;
+    HTMLStackElem* residualStyleStack = 0;
+    unsigned stackDepth = 1;
+    unsigned redundantStyleCount = 0;
+    while (curr && curr != maxElem) {
+        // We will actually schedule this tag for reopening
+        // after we complete the close of this entire block.
+        if (isResidualStyleTag(curr->tagName) && stackDepth++ < cResidualStyleMaxDepth) {
+            // We've overloaded the use of stack elements and are just reusing the
+            // struct with a slightly different meaning to the variables.  Instead of chaining
+            // from innermost to outermost, we build up a list of all the tags we need to reopen
+            // from the outermost to the innermost, i.e., residualStyleStack will end up pointing
+            // to the outermost tag we need to reopen.
+            // We also set curr->node to be the actual element that corresponds to the ID stored in
+            // curr->id rather than the node that you should pop to when the element gets pulled off
+            // the stack.
+            if (residualStyleStack && curr->tagName == residualStyleStack->tagName && curr->node->attributes()->mapsEquivalent(residualStyleStack->node->attributes()))
+                redundantStyleCount++;
+            else
+                redundantStyleCount = 0;
+
+            if (redundantStyleCount < cMaxRedundantTagDepth)
+                moveOneBlockToStack(residualStyleStack);
+            else
+                popOneBlock();
+        } else
+            popOneBlock();
+
+        curr = m_blockStack;
+    }
+
+    reopenResidualStyleTags(residualStyleStack, 0); // Stray table content can't be an issue here, since some element above will always become the root of new stray table content.
+
+    m_handlingResidualStyleAcrossBlocks = false;
+}
+
+void LegacyHTMLTreeBuilder::reopenResidualStyleTags(HTMLStackElem* elem, Node* malformedTableParent)
+{
+    // Loop for each tag that needs to be reopened.
+    while (elem) {
+        // Create a shallow clone of the DOM node for this element.
+        RefPtr<Node> newNode = elem->node->cloneNode(false); 
+        reportError(ResidualStyleError, &newNode->localName());
+
+        // Append the new node. In the malformed table case, we need to insert before the table,
+        // which will be the last child.
+        ExceptionCode ec = 0;
+        if (malformedTableParent)
+            malformedTableParent->insertBefore(newNode, malformedTableParent->lastChild(), ec);
+        else
+            m_current->appendChild(newNode, ec);
+        // FIXME: Is it really OK to ignore the exceptions here?
+
+        // Now push a new stack element for this node we just created.
+        pushBlock(elem->tagName, elem->level);
+        newNode->beginParsingChildren();
+
+        // Set our strayTableContent boolean if needed, so that the reopened tag also knows
+        // that it is inside a malformed table.
+        m_blockStack->strayTableContent = malformedTableParent != 0;
+        if (m_blockStack->strayTableContent)
+            m_inStrayTableContent++;
+
+        // Clear our malformed table parent variable.
+        malformedTableParent = 0;
+
+        // Update |current| manually to point to the new node.
+        setCurrent(newNode.get());
+        
+        // Advance to the next tag that needs to be reopened.
+        HTMLStackElem* next = elem->next;
+        elem->derefNode();
+        delete elem;
+        elem = next;
+    }
+}
+
+void LegacyHTMLTreeBuilder::pushBlock(const AtomicString& tagName, int level)
+{
+    m_blockStack = new HTMLStackElem(tagName, level, m_current, m_didRefCurrent, m_blockStack);
+    if (level >= minBlockLevelTagPriority)
+        m_blocksInStack++;
+    m_treeDepth++;
+    m_didRefCurrent = false;
+    if (tagName == pTag)
+        m_hasPElementInScope = InScope;
+    else if (isScopingTag(tagName))
+        m_hasPElementInScope = NotInScope;
+}
+
+void LegacyHTMLTreeBuilder::popBlock(const AtomicString& tagName, bool reportErrors)
+{
+    HTMLStackElem* elem = m_blockStack;
+
+    if (m_parserQuirks && elem && !m_parserQuirks->shouldPopBlock(elem->tagName, tagName))
+        return;
+
+    int maxLevel = 0;
+
+    while (elem && (elem->tagName != tagName)) {
+        if (maxLevel < elem->level)
+            maxLevel = elem->level;
+        elem = elem->next;
+    }
+
+    if (!elem) {
+        if (reportErrors)
+            reportError(StrayCloseTagError, &tagName, 0, true);
+        return;
+    }
+
+    if (maxLevel > elem->level) {
+        // We didn't match because the tag is in a different scope, e.g.,
+        // <b><p>Foo</b>.  Try to correct the problem.
+        if (!isResidualStyleTag(tagName))
+            return;
+        return handleResidualStyleCloseTagAcrossBlocks(elem);
+    }
+
+    bool isAffectedByStyle = isAffectedByResidualStyle(elem->tagName);
+    HTMLStackElem* residualStyleStack = 0;
+    Node* malformedTableParent = 0;
+    
+    elem = m_blockStack;
+    unsigned stackDepth = 1;
+    unsigned redundantStyleCount = 0;
+    while (elem) {
+        if (elem->tagName == tagName) {
+            int strayTable = m_inStrayTableContent;
+            popOneBlock();
+            elem = 0;
+
+            // This element was the root of some malformed content just inside an implicit or
+            // explicit <tbody> or <tr>.
+            // If we end up needing to reopen residual style tags, the root of the reopened chain
+            // must also know that it is the root of malformed content inside a <tbody>/<tr>.
+            if (strayTable && (m_inStrayTableContent < strayTable) && residualStyleStack) {
+                Node* curr = m_current;
+                while (curr && !curr->hasTagName(tableTag))
+                    curr = curr->parentNode();
+                malformedTableParent = curr ? curr->parentNode() : 0;
+            }
+        }
+        else {
+            if (m_currentFormElement && elem->tagName == formTag)
+                // A <form> is being closed prematurely (and this is
+                // malformed HTML).  Set an attribute on the form to clear out its
+                // bottom margin.
+                m_currentFormElement->setMalformed(true);
+
+            // Schedule this tag for reopening
+            // after we complete the close of this entire block.
+            if (isAffectedByStyle && isResidualStyleTag(elem->tagName) && stackDepth++ < cResidualStyleMaxDepth) {
+                // We've overloaded the use of stack elements and are just reusing the
+                // struct with a slightly different meaning to the variables.  Instead of chaining
+                // from innermost to outermost, we build up a list of all the tags we need to reopen
+                // from the outermost to the innermost, i.e., residualStyleStack will end up pointing
+                // to the outermost tag we need to reopen.
+                // We also set elem->node to be the actual element that corresponds to the ID stored in
+                // elem->id rather than the node that you should pop to when the element gets pulled off
+                // the stack.
+                if (residualStyleStack && elem->tagName == residualStyleStack->tagName && elem->node->attributes()->mapsEquivalent(residualStyleStack->node->attributes()))
+                    redundantStyleCount++;
+                else
+                    redundantStyleCount = 0;
+
+                if (redundantStyleCount < cMaxRedundantTagDepth)
+                    moveOneBlockToStack(residualStyleStack);
+                else
+                    popOneBlock();
+            } else
+                popOneBlock();
+            elem = m_blockStack;
+        }
+    }
+
+    reopenResidualStyleTags(residualStyleStack, malformedTableParent);
+}
+
+inline HTMLStackElem* LegacyHTMLTreeBuilder::popOneBlockCommon()
+{
+    HTMLStackElem* elem = m_blockStack;
+
+    // Form elements restore their state during the parsing process.
+    // Also, a few elements (<applet>, <object>) need to know when all child elements (<param>s) are available.
+    if (m_current && elem->node != m_current)
+        m_current->finishParsingChildren();
+
+    if (m_blockStack->level >= minBlockLevelTagPriority) {
+        ASSERT(m_blocksInStack > 0);
+        m_blocksInStack--;
+    }
+    m_treeDepth--;
+    m_blockStack = elem->next;
+    m_current = elem->node;
+    m_didRefCurrent = elem->didRefNode;
+
+    if (elem->strayTableContent)
+        m_inStrayTableContent--;
+
+    if (elem->tagName == pTag)
+        m_hasPElementInScope = NotInScope;
+    else if (isScopingTag(elem->tagName))
+        m_hasPElementInScope = Unknown;
+
+    return elem;
+}
+
+void LegacyHTMLTreeBuilder::popOneBlock()
+{
+    // Store the current node before popOneBlockCommon overwrites it.
+    Node* lastCurrent = m_current;
+    bool didRefLastCurrent = m_didRefCurrent;
+
+    delete popOneBlockCommon();
+
+    if (didRefLastCurrent)
+        lastCurrent->deref();
+}
+
+void LegacyHTMLTreeBuilder::moveOneBlockToStack(HTMLStackElem*& head)
+{
+    // We'll be using the stack element we're popping, but for the current node.
+    // See the two callers for details.
+
+    // Store the current node before popOneBlockCommon overwrites it.
+    Node* lastCurrent = m_current;
+    bool didRefLastCurrent = m_didRefCurrent;
+
+    // Pop the block, but don't deref the current node as popOneBlock does because
+    // we'll be using the pointer in the new stack element.
+    HTMLStackElem* elem = popOneBlockCommon();
+
+    // Transfer the current node into the stack element.
+    // No need to deref the old elem->node because popOneBlockCommon transferred
+    // it into the m_current/m_didRefCurrent fields.
+    elem->node = lastCurrent;
+    elem->didRefNode = didRefLastCurrent;
+    elem->next = head;
+    head = elem;
+}
+
+void LegacyHTMLTreeBuilder::checkIfHasPElementInScope()
+{
+    m_hasPElementInScope = NotInScope;
+    HTMLStackElem* elem = m_blockStack;
+    while (elem) {
+        const AtomicString& tagName = elem->tagName;
+        if (tagName == pTag) {
+            m_hasPElementInScope = InScope;
+            return;
+        } else if (isScopingTag(tagName))
+            return;
+        elem = elem->next;
+    }
+}
+
+void LegacyHTMLTreeBuilder::popInlineBlocks()
+{
+    while (m_blockStack && isInline(m_current))
+        popOneBlock();
+}
+
+void LegacyHTMLTreeBuilder::freeBlock()
+{
+    while (m_blockStack)
+        popOneBlock();
+    ASSERT(!m_blocksInStack);
+    ASSERT(!m_treeDepth);
+}
+
+void LegacyHTMLTreeBuilder::createHead()
+{
+    if (m_head)
+        return;
+
+    if (!m_document->documentElement() && !m_isParsingFragment) {
+        insertNode(HTMLHtmlElement::create(m_document).get());
+        ASSERT(m_document->documentElement() || m_isParsingFragment);
+    }
+
+    m_head = HTMLHeadElement::create(m_document);
+
+    if (m_isParsingFragment)
+        return;
+
+    HTMLElement* body = m_document->body();
+    ExceptionCode ec = 0;
+    m_document->documentElement()->insertBefore(m_head.get(), body, ec);
+    if (ec)
+        m_head = 0;
+        
+    // If the body does not exist yet, then the <head> should be pushed as the current block.
+    if (m_head && !body) {
+        pushBlock(m_head->localName(), m_head->tagPriority());
+        setCurrent(m_head.get());
+    }
+}
+
+PassRefPtr<Node> LegacyHTMLTreeBuilder::handleIsindex(Token* t)
+{
+    RefPtr<Node> n = HTMLDivElement::create(m_document);
+
+    NamedNodeMap* attrs = t->attrs.get();
+
+    RefPtr<HTMLIsIndexElement> isIndex = HTMLIsIndexElement::create(m_document, m_currentFormElement.get());
+    isIndex->setAttributeMap(attrs);
+    isIndex->setAttribute(typeAttr, "khtml_isindex");
+
+    String text = searchableIndexIntroduction();
+    if (attrs) {
+        if (Attribute* a = attrs->getAttributeItem(promptAttr))
+            text = a->value().string() + " ";
+        t->attrs = 0;
+    }
+
+    n->legacyParserAddChild(HTMLHRElement::create(m_document));
+    n->legacyParserAddChild(Text::create(m_document, text));
+    n->legacyParserAddChild(isIndex.release());
+    n->legacyParserAddChild(HTMLHRElement::create(m_document));
+
+    return n.release();
+}
+
+void LegacyHTMLTreeBuilder::startBody()
+{
+    if (m_inBody)
+        return;
+
+    m_inBody = true;
+
+    if (m_isindexElement) {
+        insertNode(m_isindexElement.get(), true /* don't descend into this node */);
+        m_isindexElement = 0;
+    }
+}
+
+void LegacyHTMLTreeBuilder::finished()
+{
+    // In the case of a completely empty document, here's the place to create the HTML element.
+    if (m_current && m_current->isDocumentNode() && !m_document->documentElement())
+        insertNode(HTMLHtmlElement::create(m_document).get());
+
+    // This ensures that "current" is not left pointing to a node when the document is destroyed.
+    freeBlock();
+    setCurrent(0);
+
+    // Warning, this may delete the parser, so don't try to do anything else after this.
+    if (!m_isParsingFragment)
+        m_document->finishedParsing();
+}
+
+void LegacyHTMLTreeBuilder::reportErrorToConsole(HTMLParserErrorCode errorCode, const AtomicString* tagName1, const AtomicString* tagName2, bool closeTags)
+{    
+    Frame* frame = m_document->frame();
+    if (!frame)
+        return;
+
+    ScriptableDocumentParser* parser = m_document->scriptableDocumentParser();
+    int lineNumber = parser->lineNumber() + 1;
+
+    AtomicString tag1;
+    AtomicString tag2;
+    if (tagName1) {
+        if (*tagName1 == "#text")
+            tag1 = "Text";
+        else if (*tagName1 == "#comment")
+            tag1 = "<!-- comment -->";
+        else
+            tag1 = (closeTags ? "</" : "<") + *tagName1 + ">";
+    }
+    if (tagName2) {
+        if (*tagName2 == "#text")
+            tag2 = "Text";
+        else if (*tagName2 == "#comment")
+            tag2 = "<!-- comment -->";
+        else
+            tag2 = (closeTags ? "</" : "<") + *tagName2 + ">";
+    }
+        
+    const char* errorMsg = htmlParserErrorMessageTemplate(errorCode);
+    if (!errorMsg)
+        return;
+
+    String message;
+    if (parser->processingContentWrittenByScript())
+        message += htmlParserDocumentWriteMessage();
+    message += errorMsg;
+    message.replace("%tag1", tag1);
+    message.replace("%tag2", tag2);
+
+    frame->domWindow()->console()->addMessage(HTMLMessageSource, LogMessageType, 
+        isWarning(errorCode) ? WarningMessageLevel : ErrorMessageLevel,
+        message, lineNumber, m_document->url().string());
+}
+
+#ifdef BUILDING_ON_LEOPARD
+bool shouldCreateImplicitHead(Document* document)
+{
+    ASSERT(document);
+    
+    Settings* settings = document->page() ? document->page()->settings() : 0;
+    return settings ? !settings->needsLeopardMailQuirks() : true;
+}
+#elif defined(BUILDING_ON_TIGER)
+bool shouldCreateImplicitHead(Document* document)
+{
+    ASSERT(document);
+    
+    Settings* settings = document->page() ? document->page()->settings() : 0;
+    return settings ? !settings->needsTigerMailQuirks() : true;
+}
+#endif
+
+
+String serializeForNumberType(double number)
+{
+    // According to HTML5, "the best representation of the number n as a floating
+    // point number" is a string produced by applying ToString() to n.
+    DtoaBuffer buffer;
+    unsigned length;
+    doubleToStringInJavaScriptFormat(number, buffer, &length);
+    return String(buffer, length);
+}
+
+bool parseToDoubleForNumberType(const String& src, double* out)
+{
+    // See HTML5 2.4.4.3 `Real numbers.'
+
+    if (src.isEmpty())
+        return false;
+    // String::toDouble() accepts leading + \t \n \v \f \r and SPACE, which are invalid in HTML5.
+    // So, check the first character.
+    if (src[0] != '-' && (src[0] < '0' || src[0] > '9'))
+        return false;
+
+    bool valid = false;
+    double value = src.toDouble(&valid);
+    if (!valid)
+        return false;
+    // NaN and Infinity are not valid numbers according to the standard.
+    if (!isfinite(value))
+        return false;
+    // -0 -> 0
+    if (!value)
+        value = 0;
+    if (out)
+        *out = value;
+    return true;
+}
+
+}