diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
new file mode 100644
index 0000000..1ea9515
--- /dev/null
+++ b/Source/core/dom/Element.cpp
@@ -0,0 +1,3123 @@
+/*
+ * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
+ *           (C) 1999 Antti Koivisto (koivisto@kde.org)
+ *           (C) 2001 Peter Kelly (pmk@post.com)
+ *           (C) 2001 Dirk Mueller (mueller@kde.org)
+ *           (C) 2007 David Smith (catfish.man@gmail.com)
+ * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
+ *           (C) 2007 Eric Seidel (eric@webkit.org)
+ *
+ * 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 "core/dom/Element.h"
+
+#include "HTMLNames.h"
+#include "XMLNSNames.h"
+#include "XMLNames.h"
+#include "core/accessibility/AXObjectCache.h"
+#include "core/css/CSSParser.h"
+#include "core/css/CSSSelectorList.h"
+#include "core/css/StylePropertySet.h"
+#include "core/css/StyleResolver.h"
+#include "core/dom/Attr.h"
+#include "core/dom/ClientRect.h"
+#include "core/dom/ClientRectList.h"
+#include "core/dom/CustomElementRegistry.h"
+#include "core/dom/DatasetDOMStringMap.h"
+#include "core/dom/Document.h"
+#include "core/dom/DocumentFragment.h"
+#include "core/dom/DocumentSharedObjectPool.h"
+#include "core/dom/ElementRareData.h"
+#include "core/dom/ExceptionCode.h"
+#include "core/dom/MutationObserverInterestGroup.h"
+#include "core/dom/MutationRecord.h"
+#include "core/dom/NamedNodeMap.h"
+#include "core/dom/NodeList.h"
+#include "core/dom/NodeRenderStyle.h"
+#include "core/dom/NodeRenderingContext.h"
+#include "core/dom/NodeTraversal.h"
+#include "core/dom/PseudoElement.h"
+#include "core/dom/SelectorQuery.h"
+#include "core/dom/ShadowRoot.h"
+#include "core/dom/Text.h"
+#include "core/dom/WebCoreMemoryInstrumentation.h"
+#include "core/editing/FrameSelection.h"
+#include "core/editing/TextIterator.h"
+#include "core/editing/htmlediting.h"
+#include "core/html/ClassList.h"
+#include "core/html/DOMTokenList.h"
+#include "core/html/HTMLCollection.h"
+#include "core/html/HTMLDocument.h"
+#include "core/html/HTMLElement.h"
+#include "core/html/HTMLFormControlsCollection.h"
+#include "core/html/HTMLFrameOwnerElement.h"
+#include "core/html/HTMLLabelElement.h"
+#include "core/html/HTMLOptionsCollection.h"
+#include "core/html/HTMLTableRowsCollection.h"
+#include "core/html/VoidCallback.h"
+#include "core/html/parser/HTMLParserIdioms.h"
+#include "core/html/shadow/InsertionPoint.h"
+#include "core/inspector/InspectorInstrumentation.h"
+#include "core/page/FocusController.h"
+#include "core/page/Frame.h"
+#include "core/page/FrameView.h"
+#include "core/page/Page.h"
+#include "core/page/PointerLockController.h"
+#include "core/page/Settings.h"
+#include "core/rendering/FlowThreadController.h"
+#include "core/rendering/RenderRegion.h"
+#include "core/rendering/RenderView.h"
+#include "core/rendering/RenderWidget.h"
+#include <wtf/BitVector.h>
+#include <wtf/MemoryInstrumentationVector.h>
+#include <wtf/text/CString.h>
+
+#if ENABLE(SVG)
+#include "SVGNames.h"
+#include "core/svg/SVGDocumentExtensions.h"
+#include "core/svg/SVGElement.h"
+#endif
+
+namespace WebCore {
+
+using namespace HTMLNames;
+using namespace XMLNames;
+
+static inline bool shouldIgnoreAttributeCase(const Element* e)
+{
+    return e && e->document()->isHTMLDocument() && e->isHTMLElement();
+}
+    
+class StyleResolverParentPusher {
+public:
+    StyleResolverParentPusher(Element* parent)
+        : m_parent(parent)
+        , m_pushedStyleResolver(0)
+    {
+    }
+    void push()
+    {
+        if (m_pushedStyleResolver)
+            return;
+        m_pushedStyleResolver = m_parent->document()->styleResolver();
+        m_pushedStyleResolver->pushParentElement(m_parent);
+    }
+    ~StyleResolverParentPusher()
+    {
+
+        if (!m_pushedStyleResolver)
+            return;
+
+        // This tells us that our pushed style selector is in a bad state,
+        // so we should just bail out in that scenario.
+        ASSERT(m_pushedStyleResolver == m_parent->document()->styleResolver());
+        if (m_pushedStyleResolver != m_parent->document()->styleResolver())
+            return;
+
+        m_pushedStyleResolver->popParentElement(m_parent);
+    }
+
+private:
+    Element* m_parent;
+    StyleResolver* m_pushedStyleResolver;
+};
+
+typedef Vector<RefPtr<Attr> > AttrNodeList;
+typedef HashMap<Element*, OwnPtr<AttrNodeList> > AttrNodeListMap;
+
+static AttrNodeListMap& attrNodeListMap()
+{
+    DEFINE_STATIC_LOCAL(AttrNodeListMap, map, ());
+    return map;
+}
+
+static AttrNodeList* attrNodeListForElement(Element* element)
+{
+    if (!element->hasSyntheticAttrChildNodes())
+        return 0;
+    ASSERT(attrNodeListMap().contains(element));
+    return attrNodeListMap().get(element);
+}
+
+static AttrNodeList* ensureAttrNodeListForElement(Element* element)
+{
+    if (element->hasSyntheticAttrChildNodes()) {
+        ASSERT(attrNodeListMap().contains(element));
+        return attrNodeListMap().get(element);
+    }
+    ASSERT(!attrNodeListMap().contains(element));
+    element->setHasSyntheticAttrChildNodes(true);
+    AttrNodeListMap::AddResult result = attrNodeListMap().add(element, adoptPtr(new AttrNodeList));
+    return result.iterator->value.get();
+}
+
+static void removeAttrNodeListForElement(Element* element)
+{
+    ASSERT(element->hasSyntheticAttrChildNodes());
+    ASSERT(attrNodeListMap().contains(element));
+    attrNodeListMap().remove(element);
+    element->setHasSyntheticAttrChildNodes(false);
+}
+
+static Attr* findAttrNodeInList(AttrNodeList* attrNodeList, const QualifiedName& name)
+{
+    for (unsigned i = 0; i < attrNodeList->size(); ++i) {
+        if (attrNodeList->at(i)->qualifiedName() == name)
+            return attrNodeList->at(i).get();
+    }
+    return 0;
+}
+
+// Need a template since ElementShadow is not a Node, but has the style recalc methods.
+template<class T>
+static inline bool shouldRecalcStyle(Node::StyleChange change, const T* node)
+{
+    return change >= Node::Inherit || node->childNeedsStyleRecalc() || node->needsStyleRecalc();
+}
+
+PassRefPtr<Element> Element::create(const QualifiedName& tagName, Document* document)
+{
+    return adoptRef(new Element(tagName, document, CreateElement));
+}
+
+Element::~Element()
+{
+#ifndef NDEBUG
+    if (document() && document()->renderer()) {
+        // When the document is not destroyed, an element that was part of a named flow
+        // content nodes should have been removed from the content nodes collection
+        // and the inNamedFlow flag reset.
+        ASSERT(!inNamedFlow());
+    }
+#endif
+
+    if (hasRareData()) {
+        ElementRareData* data = elementRareData();
+        data->setPseudoElement(BEFORE, 0);
+        data->setPseudoElement(AFTER, 0);
+        data->clearShadow();
+    }
+
+    if (isCustomElement() && document() && document()->registry()) {
+        document()->registry()->customElementWasDestroyed(this);
+    }
+
+    if (hasSyntheticAttrChildNodes())
+        detachAllAttrNodesFromElement();
+
+#if ENABLE(SVG)
+    if (hasPendingResources()) {
+        document()->accessSVGExtensions()->removeElementFromPendingResources(this);
+        ASSERT(!hasPendingResources());
+    }
+#endif
+}
+
+inline ElementRareData* Element::elementRareData() const
+{
+    ASSERT(hasRareData());
+    return static_cast<ElementRareData*>(rareData());
+}
+
+inline ElementRareData* Element::ensureElementRareData()
+{
+    return static_cast<ElementRareData*>(ensureRareData());
+}
+
+void Element::clearTabIndexExplicitlyIfNeeded()
+{
+    if (hasRareData())
+        elementRareData()->clearTabIndexExplicitly();
+}
+
+void Element::setTabIndexExplicitly(short tabIndex)
+{
+    ensureElementRareData()->setTabIndexExplicitly(tabIndex);
+}
+
+bool Element::supportsFocus() const
+{
+    return hasRareData() && elementRareData()->tabIndexSetExplicitly();
+}
+
+short Element::tabIndex() const
+{
+    return hasRareData() ? elementRareData()->tabIndex() : 0;
+}
+
+DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, blur);
+DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, error);
+DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, focus);
+DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, load);
+
+PassRefPtr<Node> Element::cloneNode(bool deep)
+{
+    return deep ? cloneElementWithChildren() : cloneElementWithoutChildren();
+}
+
+PassRefPtr<Element> Element::cloneElementWithChildren()
+{
+    RefPtr<Element> clone = cloneElementWithoutChildren();
+    cloneChildNodes(clone.get());
+    return clone.release();
+}
+
+PassRefPtr<Element> Element::cloneElementWithoutChildren()
+{
+    RefPtr<Element> clone = cloneElementWithoutAttributesAndChildren();
+    // This will catch HTML elements in the wrong namespace that are not correctly copied.
+    // This is a sanity check as HTML overloads some of the DOM methods.
+    ASSERT(isHTMLElement() == clone->isHTMLElement());
+
+    clone->cloneDataFromElement(*this);
+    return clone.release();
+}
+
+PassRefPtr<Element> Element::cloneElementWithoutAttributesAndChildren()
+{
+    return document()->createElement(tagQName(), false);
+}
+
+PassRefPtr<Attr> Element::detachAttribute(size_t index)
+{
+    ASSERT(elementData());
+
+    const Attribute* attribute = elementData()->attributeItem(index);
+    ASSERT(attribute);
+
+    RefPtr<Attr> attrNode = attrIfExists(attribute->name());
+    if (attrNode)
+        detachAttrNodeFromElementWithValue(attrNode.get(), attribute->value());
+    else
+        attrNode = Attr::create(document(), attribute->name(), attribute->value());
+
+    removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
+    return attrNode.release();
+}
+
+void Element::removeAttribute(const QualifiedName& name)
+{
+    if (!elementData())
+        return;
+
+    size_t index = elementData()->getAttributeItemIndex(name);
+    if (index == notFound)
+        return;
+
+    removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
+}
+
+void Element::setBooleanAttribute(const QualifiedName& name, bool value)
+{
+    if (value)
+        setAttribute(name, emptyAtom);
+    else
+        removeAttribute(name);
+}
+
+NamedNodeMap* Element::attributes() const
+{
+    ElementRareData* rareData = const_cast<Element*>(this)->ensureElementRareData();
+    if (NamedNodeMap* attributeMap = rareData->attributeMap())
+        return attributeMap;
+
+    rareData->setAttributeMap(NamedNodeMap::create(const_cast<Element*>(this)));
+    return rareData->attributeMap();
+}
+
+Node::NodeType Element::nodeType() const
+{
+    return ELEMENT_NODE;
+}
+
+bool Element::hasAttribute(const QualifiedName& name) const
+{
+    return hasAttributeNS(name.namespaceURI(), name.localName());
+}
+
+void Element::synchronizeAllAttributes() const
+{
+    if (!elementData())
+        return;
+    if (elementData()->m_styleAttributeIsDirty) {
+        ASSERT(isStyledElement());
+        static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
+    }
+#if ENABLE(SVG)
+    if (elementData()->m_animatedSVGAttributesAreDirty) {
+        ASSERT(isSVGElement());
+        toSVGElement(this)->synchronizeAnimatedSVGAttribute(anyQName());
+    }
+#endif
+}
+
+inline void Element::synchronizeAttribute(const QualifiedName& name) const
+{
+    if (!elementData())
+        return;
+    if (UNLIKELY(name == styleAttr && elementData()->m_styleAttributeIsDirty)) {
+        ASSERT(isStyledElement());
+        static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
+        return;
+    }
+#if ENABLE(SVG)
+    if (UNLIKELY(elementData()->m_animatedSVGAttributesAreDirty)) {
+        ASSERT(isSVGElement());
+        toSVGElement(this)->synchronizeAnimatedSVGAttribute(name);
+    }
+#endif
+}
+
+inline void Element::synchronizeAttribute(const AtomicString& localName) const
+{
+    // This version of synchronizeAttribute() is streamlined for the case where you don't have a full QualifiedName,
+    // e.g when called from DOM API.
+    if (!elementData())
+        return;
+    if (elementData()->m_styleAttributeIsDirty && equalPossiblyIgnoringCase(localName, styleAttr.localName(), shouldIgnoreAttributeCase(this))) {
+        ASSERT(isStyledElement());
+        static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
+        return;
+    }
+#if ENABLE(SVG)
+    if (elementData()->m_animatedSVGAttributesAreDirty) {
+        // We're not passing a namespace argument on purpose. SVGNames::*Attr are defined w/o namespaces as well.
+        ASSERT(isSVGElement());
+        static_cast<const SVGElement*>(this)->synchronizeAnimatedSVGAttribute(QualifiedName(nullAtom, localName, nullAtom));
+    }
+#endif
+}
+
+const AtomicString& Element::getAttribute(const QualifiedName& name) const
+{
+    if (!elementData())
+        return nullAtom;
+    synchronizeAttribute(name);
+    if (const Attribute* attribute = getAttributeItem(name))
+        return attribute->value();
+    return nullAtom;
+}
+
+void Element::scrollIntoView(bool alignToTop) 
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (!renderer())
+        return;
+
+    LayoutRect bounds = boundingBox();
+    // Align to the top / bottom and to the closest edge.
+    if (alignToTop)
+        renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignTopAlways);
+    else
+        renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignBottomAlways);
+}
+
+void Element::scrollIntoViewIfNeeded(bool centerIfNeeded)
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (!renderer())
+        return;
+
+    LayoutRect bounds = boundingBox();
+    if (centerIfNeeded)
+        renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignCenterIfNeeded, ScrollAlignment::alignCenterIfNeeded);
+    else
+        renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignToEdgeIfNeeded);
+}
+
+void Element::scrollByUnits(int units, ScrollGranularity granularity)
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (!renderer())
+        return;
+
+    if (!renderer()->hasOverflowClip())
+        return;
+
+    ScrollDirection direction = ScrollDown;
+    if (units < 0) {
+        direction = ScrollUp;
+        units = -units;
+    }
+    Node* stopNode = this;
+    toRenderBox(renderer())->scroll(direction, granularity, units, &stopNode);
+}
+
+void Element::scrollByLines(int lines)
+{
+    scrollByUnits(lines, ScrollByLine);
+}
+
+void Element::scrollByPages(int pages)
+{
+    scrollByUnits(pages, ScrollByPage);
+}
+
+static float localZoomForRenderer(RenderObject* renderer)
+{
+    // FIXME: This does the wrong thing if two opposing zooms are in effect and canceled each
+    // other out, but the alternative is that we'd have to crawl up the whole render tree every
+    // time (or store an additional bit in the RenderStyle to indicate that a zoom was specified).
+    float zoomFactor = 1;
+    if (renderer->style()->effectiveZoom() != 1) {
+        // Need to find the nearest enclosing RenderObject that set up
+        // a differing zoom, and then we divide our result by it to eliminate the zoom.
+        RenderObject* prev = renderer;
+        for (RenderObject* curr = prev->parent(); curr; curr = curr->parent()) {
+            if (curr->style()->effectiveZoom() != prev->style()->effectiveZoom()) {
+                zoomFactor = prev->style()->zoom();
+                break;
+            }
+            prev = curr;
+        }
+        if (prev->isRenderView())
+            zoomFactor = prev->style()->zoom();
+    }
+    return zoomFactor;
+}
+
+static int adjustForLocalZoom(LayoutUnit value, RenderObject* renderer)
+{
+    float zoomFactor = localZoomForRenderer(renderer);
+    if (zoomFactor == 1)
+        return value;
+    return lroundf(value / zoomFactor);
+}
+
+int Element::offsetLeft()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBoxModelObject* renderer = renderBoxModelObject())
+        return adjustForLocalZoom(renderer->pixelSnappedOffsetLeft(), renderer);
+    return 0;
+}
+
+int Element::offsetTop()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBoxModelObject* renderer = renderBoxModelObject())
+        return adjustForLocalZoom(renderer->pixelSnappedOffsetTop(), renderer);
+    return 0;
+}
+
+int Element::offsetWidth()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBoxModelObject* renderer = renderBoxModelObject())
+        return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedOffsetWidth(), renderer).round();
+    return 0;
+}
+
+int Element::offsetHeight()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBoxModelObject* renderer = renderBoxModelObject())
+        return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedOffsetHeight(), renderer).round();
+    return 0;
+}
+
+Element* Element::bindingsOffsetParent()
+{
+    Element* element = offsetParent();
+    if (!element || !element->isInShadowTree())
+        return element;
+    return element->containingShadowRoot()->type() == ShadowRoot::UserAgentShadowRoot ? 0 : element;
+}
+
+Element* Element::offsetParent()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderObject* renderer = this->renderer())
+        return renderer->offsetParent();
+    return 0;
+}
+
+int Element::clientLeft()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (RenderBox* renderer = renderBox())
+        return adjustForAbsoluteZoom(roundToInt(renderer->clientLeft()), renderer);
+    return 0;
+}
+
+int Element::clientTop()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (RenderBox* renderer = renderBox())
+        return adjustForAbsoluteZoom(roundToInt(renderer->clientTop()), renderer);
+    return 0;
+}
+
+int Element::clientWidth()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    // When in strict mode, clientWidth for the document element should return the width of the containing frame.
+    // When in quirks mode, clientWidth for the body element should return the width of the containing frame.
+    bool inQuirksMode = document()->inQuirksMode();
+    if ((!inQuirksMode && document()->documentElement() == this) ||
+        (inQuirksMode && isHTMLElement() && document()->body() == this)) {
+        if (FrameView* view = document()->view()) {
+            if (RenderView* renderView = document()->renderView())
+                return adjustForAbsoluteZoom(view->layoutWidth(), renderView);
+        }
+    }
+    
+    if (RenderBox* renderer = renderBox())
+        return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedClientWidth(), renderer).round();
+    return 0;
+}
+
+int Element::clientHeight()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    // When in strict mode, clientHeight for the document element should return the height of the containing frame.
+    // When in quirks mode, clientHeight for the body element should return the height of the containing frame.
+    bool inQuirksMode = document()->inQuirksMode();     
+
+    if ((!inQuirksMode && document()->documentElement() == this) ||
+        (inQuirksMode && isHTMLElement() && document()->body() == this)) {
+        if (FrameView* view = document()->view()) {
+            if (RenderView* renderView = document()->renderView())
+                return adjustForAbsoluteZoom(view->layoutHeight(), renderView);
+        }
+    }
+    
+    if (RenderBox* renderer = renderBox())
+        return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedClientHeight(), renderer).round();
+    return 0;
+}
+
+int Element::scrollLeft()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        return adjustForAbsoluteZoom(rend->scrollLeft(), rend);
+    return 0;
+}
+
+int Element::scrollTop()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        return adjustForAbsoluteZoom(rend->scrollTop(), rend);
+    return 0;
+}
+
+void Element::setScrollLeft(int newLeft)
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        rend->setScrollLeft(static_cast<int>(newLeft * rend->style()->effectiveZoom()));
+}
+
+void Element::setScrollTop(int newTop)
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        rend->setScrollTop(static_cast<int>(newTop * rend->style()->effectiveZoom()));
+}
+
+int Element::scrollWidth()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        return adjustForAbsoluteZoom(rend->scrollWidth(), rend);
+    return 0;
+}
+
+int Element::scrollHeight()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+    if (RenderBox* rend = renderBox())
+        return adjustForAbsoluteZoom(rend->scrollHeight(), rend);
+    return 0;
+}
+
+IntRect Element::boundsInRootViewSpace()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    FrameView* view = document()->view();
+    if (!view)
+        return IntRect();
+
+    Vector<FloatQuad> quads;
+#if ENABLE(SVG)
+    if (isSVGElement() && renderer()) {
+        // Get the bounding rectangle from the SVG model.
+        SVGElement* svgElement = toSVGElement(this);
+        FloatRect localRect;
+        if (svgElement->getBoundingBox(localRect))
+            quads.append(renderer()->localToAbsoluteQuad(localRect));
+    } else
+#endif
+    {
+        // Get the bounding rectangle from the box model.
+        if (renderBoxModelObject())
+            renderBoxModelObject()->absoluteQuads(quads);
+    }
+
+    if (quads.isEmpty())
+        return IntRect();
+
+    IntRect result = quads[0].enclosingBoundingBox();
+    for (size_t i = 1; i < quads.size(); ++i)
+        result.unite(quads[i].enclosingBoundingBox());
+
+    result = view->contentsToRootView(result);
+    return result;
+}
+
+PassRefPtr<ClientRectList> Element::getClientRects()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    RenderBoxModelObject* renderBoxModelObject = this->renderBoxModelObject();
+    if (!renderBoxModelObject)
+        return ClientRectList::create();
+
+    // FIXME: Handle SVG elements.
+    // FIXME: Handle table/inline-table with a caption.
+
+    Vector<FloatQuad> quads;
+    renderBoxModelObject->absoluteQuads(quads);
+    document()->adjustFloatQuadsForScrollAndAbsoluteZoom(quads, renderBoxModelObject);
+    return ClientRectList::create(quads);
+}
+
+PassRefPtr<ClientRect> Element::getBoundingClientRect()
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    Vector<FloatQuad> quads;
+#if ENABLE(SVG)
+    if (isSVGElement() && renderer() && !renderer()->isSVGRoot()) {
+        // Get the bounding rectangle from the SVG model.
+        SVGElement* svgElement = toSVGElement(this);
+        FloatRect localRect;
+        if (svgElement->getBoundingBox(localRect))
+            quads.append(renderer()->localToAbsoluteQuad(localRect));
+    } else
+#endif
+    {
+        // Get the bounding rectangle from the box model.
+        if (renderBoxModelObject())
+            renderBoxModelObject()->absoluteQuads(quads);
+    }
+
+    if (quads.isEmpty())
+        return ClientRect::create();
+
+    FloatRect result = quads[0].boundingBox();
+    for (size_t i = 1; i < quads.size(); ++i)
+        result.unite(quads[i].boundingBox());
+
+    document()->adjustFloatRectForScrollAndAbsoluteZoom(result, renderer());
+    return ClientRect::create(result);
+}
+    
+IntRect Element::screenRect() const
+{
+    if (!renderer())
+        return IntRect();
+    // FIXME: this should probably respect transforms
+    return document()->view()->contentsToScreen(renderer()->absoluteBoundingBoxRectIgnoringTransforms());
+}
+
+const AtomicString& Element::getAttribute(const AtomicString& localName) const
+{
+    if (!elementData())
+        return nullAtom;
+    synchronizeAttribute(localName);
+    if (const Attribute* attribute = elementData()->getAttributeItem(localName, shouldIgnoreAttributeCase(this)))
+        return attribute->value();
+    return nullAtom;
+}
+
+const AtomicString& Element::getAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName) const
+{
+    return getAttribute(QualifiedName(nullAtom, localName, namespaceURI));
+}
+
+void Element::setAttribute(const AtomicString& localName, const AtomicString& value, ExceptionCode& ec)
+{
+    if (!Document::isValidName(localName)) {
+        ec = INVALID_CHARACTER_ERR;
+        return;
+    }
+
+    synchronizeAttribute(localName);
+    const AtomicString& caseAdjustedLocalName = shouldIgnoreAttributeCase(this) ? localName.lower() : localName;
+
+    size_t index = elementData() ? elementData()->getAttributeItemIndex(caseAdjustedLocalName, false) : notFound;
+    const QualifiedName& qName = index != notFound ? attributeItem(index)->name() : QualifiedName(nullAtom, caseAdjustedLocalName, nullAtom);
+    setAttributeInternal(index, qName, value, NotInSynchronizationOfLazyAttribute);
+}
+
+void Element::setAttribute(const QualifiedName& name, const AtomicString& value)
+{
+    synchronizeAttribute(name);
+    size_t index = elementData() ? elementData()->getAttributeItemIndex(name) : notFound;
+    setAttributeInternal(index, name, value, NotInSynchronizationOfLazyAttribute);
+}
+
+void Element::setSynchronizedLazyAttribute(const QualifiedName& name, const AtomicString& value)
+{
+    size_t index = elementData() ? elementData()->getAttributeItemIndex(name) : notFound;
+    setAttributeInternal(index, name, value, InSynchronizationOfLazyAttribute);
+}
+
+inline void Element::setAttributeInternal(size_t index, const QualifiedName& name, const AtomicString& newValue, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
+{
+    if (newValue.isNull()) {
+        if (index != notFound)
+            removeAttributeInternal(index, inSynchronizationOfLazyAttribute);
+        return;
+    }
+
+    if (index == notFound) {
+        addAttributeInternal(name, newValue, inSynchronizationOfLazyAttribute);
+        return;
+    }
+
+    if (!inSynchronizationOfLazyAttribute)
+        willModifyAttribute(name, attributeItem(index)->value(), newValue);
+
+    if (newValue != attributeItem(index)->value()) {
+        // If there is an Attr node hooked to this attribute, the Attr::setValue() call below
+        // will write into the ElementData.
+        // FIXME: Refactor this so it makes some sense.
+        if (RefPtr<Attr> attrNode = inSynchronizationOfLazyAttribute ? 0 : attrIfExists(name))
+            attrNode->setValue(newValue);
+        else
+            ensureUniqueElementData()->attributeItem(index)->setValue(newValue);
+    }
+
+    if (!inSynchronizationOfLazyAttribute)
+        didModifyAttribute(name, newValue);
+}
+
+static inline AtomicString makeIdForStyleResolution(const AtomicString& value, bool inQuirksMode)
+{
+    if (inQuirksMode)
+        return value.lower();
+    return value;
+}
+
+static bool checkNeedsStyleInvalidationForIdChange(const AtomicString& oldId, const AtomicString& newId, StyleResolver* styleResolver)
+{
+    ASSERT(newId != oldId);
+    if (!oldId.isEmpty() && styleResolver->hasSelectorForId(oldId))
+        return true;
+    if (!newId.isEmpty() && styleResolver->hasSelectorForId(newId))
+        return true;
+    return false;
+}
+
+void Element::attributeChanged(const QualifiedName& name, const AtomicString& newValue, AttributeModificationReason)
+{
+    if (ElementShadow* parentElementShadow = shadowOfParentForDistribution(this)) {
+        if (shouldInvalidateDistributionWhenAttributeChanged(parentElementShadow, name, newValue))
+            parentElementShadow->invalidateDistribution();
+    }
+
+    parseAttribute(name, newValue);
+
+    document()->incDOMTreeVersion();
+
+    StyleResolver* styleResolver = document()->styleResolverIfExists();
+    bool testShouldInvalidateStyle = attached() && styleResolver && styleChangeType() < FullStyleChange;
+    bool shouldInvalidateStyle = false;
+
+    if (isIdAttributeName(name)) {
+        AtomicString oldId = elementData()->idForStyleResolution();
+        AtomicString newId = makeIdForStyleResolution(newValue, document()->inQuirksMode());
+        if (newId != oldId) {
+            elementData()->setIdForStyleResolution(newId);
+            shouldInvalidateStyle = testShouldInvalidateStyle && checkNeedsStyleInvalidationForIdChange(oldId, newId, styleResolver);
+        }
+    } else if (name == classAttr)
+        classAttributeChanged(newValue);
+    else if (name == HTMLNames::nameAttr)
+        setHasName(!newValue.isNull());
+    else if (name == HTMLNames::pseudoAttr)
+        shouldInvalidateStyle |= testShouldInvalidateStyle && isInShadowTree();
+
+    invalidateNodeListCachesInAncestors(&name, this);
+
+    // If there is currently no StyleResolver, we can't be sure that this attribute change won't affect style.
+    shouldInvalidateStyle |= !styleResolver;
+
+    if (shouldInvalidateStyle)
+        setNeedsStyleRecalc();
+
+    if (AXObjectCache* cache = document()->existingAXObjectCache())
+        cache->handleAttributeChanged(name, this);
+}
+
+inline void Element::attributeChangedFromParserOrByCloning(const QualifiedName& name, const AtomicString& newValue, AttributeModificationReason reason)
+{
+    if (RuntimeEnabledFeatures::customDOMElementsEnabled() && name == isAttr) {
+        document()->ensureCustomElementRegistry()->didGiveTypeExtension(this, newValue);
+    }
+    attributeChanged(name, newValue, reason);
+}
+
+template <typename CharacterType>
+static inline bool classStringHasClassName(const CharacterType* characters, unsigned length)
+{
+    ASSERT(length > 0);
+
+    unsigned i = 0;
+    do {
+        if (isNotHTMLSpace(characters[i]))
+            break;
+        ++i;
+    } while (i < length);
+
+    return i < length;
+}
+
+static inline bool classStringHasClassName(const AtomicString& newClassString)
+{
+    unsigned length = newClassString.length();
+
+    if (!length)
+        return false;
+
+    if (newClassString.is8Bit())
+        return classStringHasClassName(newClassString.characters8(), length);
+    return classStringHasClassName(newClassString.characters16(), length);
+}
+
+template<typename Checker>
+static bool checkSelectorForClassChange(const SpaceSplitString& changedClasses, const Checker& checker)
+{
+    unsigned changedSize = changedClasses.size();
+    for (unsigned i = 0; i < changedSize; ++i) {
+        if (checker.hasSelectorForClass(changedClasses[i]))
+            return true;
+    }
+    return false;
+}
+
+template<typename Checker>
+static bool checkSelectorForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, const Checker& checker)
+{
+    unsigned oldSize = oldClasses.size();
+    if (!oldSize)
+        return checkSelectorForClassChange(newClasses, checker);
+    BitVector remainingClassBits;
+    remainingClassBits.ensureSize(oldSize);
+    // Class vectors tend to be very short. This is faster than using a hash table.
+    unsigned newSize = newClasses.size();
+    for (unsigned i = 0; i < newSize; ++i) {
+        for (unsigned j = 0; j < oldSize; ++j) {
+            if (newClasses[i] == oldClasses[j]) {
+                remainingClassBits.quickSet(j);
+                continue;
+            }
+        }
+        if (checker.hasSelectorForClass(newClasses[i]))
+            return true;
+    }
+    for (unsigned i = 0; i < oldSize; ++i) {
+        // If the bit is not set the the corresponding class has been removed.
+        if (remainingClassBits.quickGet(i))
+            continue;
+        if (checker.hasSelectorForClass(oldClasses[i]))
+            return true;
+    }
+    return false;
+}
+
+void Element::classAttributeChanged(const AtomicString& newClassString)
+{
+    StyleResolver* styleResolver = document()->styleResolverIfExists();
+    bool testShouldInvalidateStyle = attached() && styleResolver && styleChangeType() < FullStyleChange;
+    bool shouldInvalidateStyle = false;
+
+    if (classStringHasClassName(newClassString)) {
+        const bool shouldFoldCase = document()->inQuirksMode();
+        const SpaceSplitString oldClasses = elementData()->classNames();
+        elementData()->setClass(newClassString, shouldFoldCase);
+        const SpaceSplitString& newClasses = elementData()->classNames();
+        shouldInvalidateStyle = testShouldInvalidateStyle && checkSelectorForClassChange(oldClasses, newClasses, *styleResolver);
+    } else {
+        const SpaceSplitString& oldClasses = elementData()->classNames();
+        shouldInvalidateStyle = testShouldInvalidateStyle && checkSelectorForClassChange(oldClasses, *styleResolver);
+        elementData()->clearClass();
+    }
+
+    if (hasRareData())
+        elementRareData()->clearClassListValueForQuirksMode();
+
+    if (shouldInvalidateStyle)
+        setNeedsStyleRecalc();
+}
+
+bool Element::shouldInvalidateDistributionWhenAttributeChanged(ElementShadow* elementShadow, const QualifiedName& name, const AtomicString& newValue)
+{
+    ASSERT(elementShadow);
+    const SelectRuleFeatureSet& featureSet = elementShadow->distributor().ensureSelectFeatureSet(elementShadow);
+
+    if (isIdAttributeName(name)) {
+        AtomicString oldId = elementData()->idForStyleResolution();
+        AtomicString newId = makeIdForStyleResolution(newValue, document()->inQuirksMode());
+        if (newId != oldId) {
+            if (!oldId.isEmpty() && featureSet.hasSelectorForId(oldId))
+                return true;
+            if (!newId.isEmpty() && featureSet.hasSelectorForId(newId))
+                return true;
+        }
+    }
+
+    if (name == HTMLNames::classAttr) {
+        const AtomicString& newClassString = newValue;
+        if (classStringHasClassName(newClassString)) {
+            const bool shouldFoldCase = document()->inQuirksMode();
+            const SpaceSplitString& oldClasses = elementData()->classNames();
+            const SpaceSplitString newClasses(newClassString, shouldFoldCase);
+            if (checkSelectorForClassChange(oldClasses, newClasses, featureSet))
+                return true;
+        } else {
+            const SpaceSplitString& oldClasses = elementData()->classNames();
+            if (checkSelectorForClassChange(oldClasses, featureSet))
+                return true;
+        }
+    }
+
+    return featureSet.hasSelectorForAttribute(name.localName());
+}
+
+// Returns true is the given attribute is an event handler.
+// We consider an event handler any attribute that begins with "on".
+// It is a simple solution that has the advantage of not requiring any
+// code or configuration change if a new event handler is defined.
+
+static inline bool isEventHandlerAttribute(const Attribute& attribute)
+{
+    return attribute.name().namespaceURI().isNull() && attribute.name().localName().startsWith("on");
+}
+
+bool Element::isJavaScriptURLAttribute(const Attribute& attribute) const
+{
+    return isURLAttribute(attribute) && protocolIsJavaScript(stripLeadingAndTrailingHTMLSpaces(attribute.value()));
+}
+
+void Element::stripScriptingAttributes(Vector<Attribute>& attributeVector) const
+{
+    size_t destination = 0;
+    for (size_t source = 0; source < attributeVector.size(); ++source) {
+        if (isEventHandlerAttribute(attributeVector[source])
+            || isJavaScriptURLAttribute(attributeVector[source])
+            || isHTMLContentAttribute(attributeVector[source]))
+            continue;
+
+        if (source != destination)
+            attributeVector[destination] = attributeVector[source];
+
+        ++destination;
+    }
+    attributeVector.shrink(destination);
+}
+
+void Element::parserSetAttributes(const Vector<Attribute>& attributeVector)
+{
+    ASSERT(!inDocument());
+    ASSERT(!parentNode());
+    ASSERT(!m_elementData);
+
+    if (attributeVector.isEmpty())
+        return;
+
+    if (document() && document()->sharedObjectPool())
+        m_elementData = document()->sharedObjectPool()->cachedShareableElementDataWithAttributes(attributeVector);
+    else
+        m_elementData = ShareableElementData::createWithAttributes(attributeVector);
+
+    // Use attributeVector instead of m_elementData because attributeChanged might modify m_elementData.
+    for (unsigned i = 0; i < attributeVector.size(); ++i)
+        attributeChangedFromParserOrByCloning(attributeVector[i].name(), attributeVector[i].value(), ModifiedDirectly);
+}
+
+bool Element::hasAttributes() const
+{
+    synchronizeAllAttributes();
+    return elementData() && elementData()->length();
+}
+
+bool Element::hasEquivalentAttributes(const Element* other) const
+{
+    synchronizeAllAttributes();
+    other->synchronizeAllAttributes();
+    if (elementData() == other->elementData())
+        return true;
+    if (elementData())
+        return elementData()->isEquivalent(other->elementData());
+    if (other->elementData())
+        return other->elementData()->isEquivalent(elementData());
+    return true;
+}
+
+String Element::nodeName() const
+{
+    return m_tagName.toString();
+}
+
+String Element::nodeNamePreservingCase() const
+{
+    return m_tagName.toString();
+}
+
+void Element::setPrefix(const AtomicString& prefix, ExceptionCode& ec)
+{
+    ec = 0;
+    checkSetPrefix(prefix, ec);
+    if (ec)
+        return;
+
+    m_tagName.setPrefix(prefix.isEmpty() ? AtomicString() : prefix);
+}
+
+KURL Element::baseURI() const
+{
+    const AtomicString& baseAttribute = getAttribute(baseAttr);
+    KURL base(KURL(), baseAttribute);
+    if (!base.protocol().isEmpty())
+        return base;
+
+    ContainerNode* parent = parentNode();
+    if (!parent)
+        return base;
+
+    const KURL& parentBase = parent->baseURI();
+    if (parentBase.isNull())
+        return base;
+
+    return KURL(parentBase, baseAttribute);
+}
+
+const AtomicString& Element::imageSourceURL() const
+{
+    return getAttribute(srcAttr);
+}
+
+bool Element::rendererIsNeeded(const NodeRenderingContext& context)
+{
+    return context.style()->display() != NONE;
+}
+
+RenderObject* Element::createRenderer(RenderArena*, RenderStyle* style)
+{
+    return RenderObject::createObject(this, style);
+}
+
+#if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
+bool Element::isDateTimeFieldElement() const
+{
+    return false;
+}
+#endif
+
+bool Element::wasChangedSinceLastFormControlChangeEvent() const
+{
+    return false;
+}
+
+void Element::setChangedSinceLastFormControlChangeEvent(bool)
+{
+}
+
+bool Element::isDisabledFormControl() const
+{
+    // FIXME: disabled and inert are separate concepts in the spec, but now we treat them as the same.
+    // For example, an inert, non-disabled form control should not be grayed out.
+    if (isInert())
+        return true;
+    return false;
+}
+
+bool Element::isInert() const
+{
+    Element* dialog = document()->activeModalDialog();
+    return dialog && !containsIncludingShadowDOM(dialog) && !dialog->containsIncludingShadowDOM(this);
+}
+
+Node::InsertionNotificationRequest Element::insertedInto(ContainerNode* insertionPoint)
+{
+    // need to do superclass processing first so inDocument() is true
+    // by the time we reach updateId
+    ContainerNode::insertedInto(insertionPoint);
+
+    if (containsFullScreenElement() && parentElement() && !parentElement()->containsFullScreenElement())
+        setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(true);
+
+    if (Element* before = pseudoElement(BEFORE))
+        before->insertedInto(insertionPoint);
+
+    if (Element* after = pseudoElement(AFTER))
+        after->insertedInto(insertionPoint);
+
+    if (!insertionPoint->isInTreeScope())
+        return InsertionDone;
+
+    if (hasRareData())
+        elementRareData()->clearClassListValueForQuirksMode();
+
+    TreeScope* scope = insertionPoint->treeScope();
+    if (scope != treeScope())
+        return InsertionDone;
+
+    const AtomicString& idValue = getIdAttribute();
+    if (!idValue.isNull())
+        updateId(scope, nullAtom, idValue);
+
+    const AtomicString& nameValue = getNameAttribute();
+    if (!nameValue.isNull())
+        updateName(nullAtom, nameValue);
+
+    if (hasTagName(labelTag)) {
+        if (scope->shouldCacheLabelsByForAttribute())
+            updateLabel(scope, nullAtom, fastGetAttribute(forAttr));
+    }
+
+    return InsertionDone;
+}
+
+void Element::removedFrom(ContainerNode* insertionPoint)
+{
+#if ENABLE(SVG)
+    bool wasInDocument = insertionPoint->document();
+#endif
+
+    if (Element* before = pseudoElement(BEFORE))
+        before->removedFrom(insertionPoint);
+
+    if (Element* after = pseudoElement(AFTER))
+        after->removedFrom(insertionPoint);
+
+    document()->removeFromTopLayer(this);
+    if (containsFullScreenElement())
+        setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(false);
+
+    if (document()->page())
+        document()->page()->pointerLockController()->elementRemoved(this);
+
+    setSavedLayerScrollOffset(IntSize());
+
+    if (insertionPoint->isInTreeScope() && treeScope() == document()) {
+        const AtomicString& idValue = getIdAttribute();
+        if (!idValue.isNull())
+            updateId(insertionPoint->treeScope(), idValue, nullAtom);
+
+        const AtomicString& nameValue = getNameAttribute();
+        if (!nameValue.isNull())
+            updateName(nameValue, nullAtom);
+
+        if (hasTagName(labelTag)) {
+            TreeScope* treeScope = insertionPoint->treeScope();
+            if (treeScope->shouldCacheLabelsByForAttribute())
+                updateLabel(treeScope, fastGetAttribute(forAttr), nullAtom);
+        }
+    }
+
+    ContainerNode::removedFrom(insertionPoint);
+#if ENABLE(SVG)
+    if (wasInDocument && hasPendingResources())
+        document()->accessSVGExtensions()->removeElementFromPendingResources(this);
+#endif
+}
+
+void Element::createRendererIfNeeded()
+{
+    NodeRenderingContext(this).createRendererForElementIfNeeded();
+}
+
+void Element::attach()
+{
+    PostAttachCallbackDisabler callbackDisabler(this);
+    StyleResolverParentPusher parentPusher(this);
+    WidgetHierarchyUpdatesSuspensionScope suspendWidgetHierarchyUpdates;
+
+    createRendererIfNeeded();
+
+    if (parentElement() && parentElement()->isInCanvasSubtree())
+        setIsInCanvasSubtree(true);
+
+    createPseudoElementIfNeeded(BEFORE);
+
+    // When a shadow root exists, it does the work of attaching the children.
+    if (ElementShadow* shadow = this->shadow()) {
+        parentPusher.push();
+        shadow->attach();
+    } else if (firstChild())
+        parentPusher.push();
+
+    ContainerNode::attach();
+
+    createPseudoElementIfNeeded(AFTER);
+
+    if (hasRareData()) {   
+        ElementRareData* data = elementRareData();
+        if (data->needsFocusAppearanceUpdateSoonAfterAttach()) {
+            if (isFocusable() && document()->focusedNode() == this)
+                document()->updateFocusAppearanceSoon(false /* don't restore selection */);
+            data->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
+        }
+    }
+}
+
+void Element::unregisterNamedFlowContentNode()
+{
+    if (RuntimeEnabledFeatures::cssRegionsEnabled() && inNamedFlow() && document()->renderView())
+        document()->renderView()->flowThreadController()->unregisterNamedFlowContentNode(this);
+}
+
+void Element::detach()
+{
+    WidgetHierarchyUpdatesSuspensionScope suspendWidgetHierarchyUpdates;
+    unregisterNamedFlowContentNode();
+    cancelFocusAppearanceUpdate();
+    if (hasRareData()) {
+        ElementRareData* data = elementRareData();
+        data->setPseudoElement(BEFORE, 0);
+        data->setPseudoElement(AFTER, 0);
+        data->setIsInCanvasSubtree(false);
+        data->resetComputedStyle();
+        data->resetDynamicRestyleObservations();
+    }
+
+    if (ElementShadow* shadow = this->shadow()) {
+        detachChildrenIfNeeded();
+        shadow->detach();
+    }
+    ContainerNode::detach();
+}
+
+bool Element::pseudoStyleCacheIsInvalid(const RenderStyle* currentStyle, RenderStyle* newStyle)
+{
+    ASSERT(currentStyle == renderStyle());
+    ASSERT(renderer());
+
+    if (!currentStyle)
+        return false;
+
+    const PseudoStyleCache* pseudoStyleCache = currentStyle->cachedPseudoStyles();
+    if (!pseudoStyleCache)
+        return false;
+
+    size_t cacheSize = pseudoStyleCache->size();
+    for (size_t i = 0; i < cacheSize; ++i) {
+        RefPtr<RenderStyle> newPseudoStyle;
+        PseudoId pseudoId = pseudoStyleCache->at(i)->styleType();
+        if (pseudoId == FIRST_LINE || pseudoId == FIRST_LINE_INHERITED)
+            newPseudoStyle = renderer()->uncachedFirstLineStyle(newStyle);
+        else
+            newPseudoStyle = renderer()->getUncachedPseudoStyle(PseudoStyleRequest(pseudoId), newStyle, newStyle);
+        if (!newPseudoStyle)
+            return true;
+        if (*newPseudoStyle != *pseudoStyleCache->at(i)) {
+            if (pseudoId < FIRST_INTERNAL_PSEUDOID)
+                newStyle->setHasPseudoStyle(pseudoId);
+            newStyle->addCachedPseudoStyle(newPseudoStyle);
+            if (pseudoId == FIRST_LINE || pseudoId == FIRST_LINE_INHERITED) {
+                // FIXME: We should do an actual diff to determine whether a repaint vs. layout
+                // is needed, but for now just assume a layout will be required.  The diff code
+                // in RenderObject::setStyle would need to be factored out so that it could be reused.
+                renderer()->setNeedsLayoutAndPrefWidthsRecalc();
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+PassRefPtr<RenderStyle> Element::styleForRenderer()
+{
+    if (hasCustomStyleCallbacks()) {
+        if (RefPtr<RenderStyle> style = customStyleForRenderer())
+            return style.release();
+    }
+
+    return document()->styleResolver()->styleForElement(this);
+}
+
+void Element::recalcStyle(StyleChange change)
+{
+    if (hasCustomStyleCallbacks())
+        willRecalcStyle(change);
+
+    // Ref currentStyle in case it would otherwise be deleted when setting the new style in the renderer.
+    RefPtr<RenderStyle> currentStyle(renderStyle());
+    bool hasParentStyle = parentNodeForRenderingAndStyle() ? static_cast<bool>(parentNodeForRenderingAndStyle()->renderStyle()) : false;
+    bool hasDirectAdjacentRules = childrenAffectedByDirectAdjacentRules();
+    bool hasIndirectAdjacentRules = childrenAffectedByForwardPositionalRules();
+
+    if ((change > NoChange || needsStyleRecalc())) {
+        if (hasRareData())
+            elementRareData()->resetComputedStyle();
+    }
+    if (hasParentStyle && (change >= Inherit || needsStyleRecalc())) {
+        StyleChange localChange = Detach;
+        RefPtr<RenderStyle> newStyle;
+        if (currentStyle) {
+            // FIXME: This still recalcs style twice when changing display types, but saves
+            // us from recalcing twice when going from none -> anything else which is more
+            // common, especially during lazy attach.
+            newStyle = styleForRenderer();
+            localChange = Node::diff(currentStyle.get(), newStyle.get(), document());
+        }
+        if (localChange == Detach) {
+            // FIXME: The style gets computed twice by calling attach. We could do better if we passed the style along.
+            reattach();
+            // attach recalculates the style for all children. No need to do it twice.
+            clearNeedsStyleRecalc();
+            clearChildNeedsStyleRecalc();
+
+            if (hasCustomStyleCallbacks())
+                didRecalcStyle(change);
+            return;
+        }
+
+        if (RenderObject* renderer = this->renderer()) {
+            if (localChange != NoChange || pseudoStyleCacheIsInvalid(currentStyle.get(), newStyle.get()) || (change == Force && renderer->requiresForcedStyleRecalcPropagation()) || styleChangeType() == SyntheticStyleChange)
+                renderer->setAnimatableStyle(newStyle.get());
+            else if (needsStyleRecalc()) {
+                // Although no change occurred, we use the new style so that the cousin style sharing code won't get
+                // fooled into believing this style is the same.
+                renderer->setStyleInternal(newStyle.get());
+            }
+        }
+
+        // If "rem" units are used anywhere in the document, and if the document element's font size changes, then go ahead and force font updating
+        // all the way down the tree. This is simpler than having to maintain a cache of objects (and such font size changes should be rare anyway).
+        if (document()->styleSheetCollection()->usesRemUnits() && document()->documentElement() == this && localChange != NoChange && currentStyle && newStyle && currentStyle->fontSize() != newStyle->fontSize()) {
+            // Cached RenderStyles may depend on the re units.
+            document()->styleResolver()->invalidateMatchedPropertiesCache();
+            change = Force;
+        }
+
+        if (change != Force) {
+            if (styleChangeType() >= FullStyleChange)
+                change = Force;
+            else
+                change = localChange;
+        }
+    }
+    StyleResolverParentPusher parentPusher(this);
+
+    // FIXME: This does not care about sibling combinators. Will be necessary in XBL2 world.
+    if (ElementShadow* shadow = this->shadow()) {
+        if (shouldRecalcStyle(change, shadow)) {
+            parentPusher.push();
+            shadow->recalcStyle(change);
+        }
+    }
+
+    if (shouldRecalcStyle(change, this))
+        updatePseudoElement(BEFORE, change);
+
+    // FIXME: This check is good enough for :hover + foo, but it is not good enough for :hover + foo + bar.
+    // For now we will just worry about the common case, since it's a lot trickier to get the second case right
+    // without doing way too much re-resolution.
+    bool forceCheckOfNextElementSibling = false;
+    bool forceCheckOfAnyElementSibling = false;
+    for (Node *n = firstChild(); n; n = n->nextSibling()) {
+        if (n->isTextNode()) {
+            toText(n)->recalcTextStyle(change);
+            continue;
+        } 
+        if (!n->isElementNode()) 
+            continue;
+        Element* element = toElement(n);
+        bool childRulesChanged = element->needsStyleRecalc() && element->styleChangeType() == FullStyleChange;
+        if ((forceCheckOfNextElementSibling || forceCheckOfAnyElementSibling))
+            element->setNeedsStyleRecalc();
+        if (shouldRecalcStyle(change, element)) {
+            parentPusher.push();
+            element->recalcStyle(change);
+        }
+        forceCheckOfNextElementSibling = childRulesChanged && hasDirectAdjacentRules;
+        forceCheckOfAnyElementSibling = forceCheckOfAnyElementSibling || (childRulesChanged && hasIndirectAdjacentRules);
+    }
+
+    if (shouldRecalcStyle(change, this))
+        updatePseudoElement(AFTER, change);
+
+    clearNeedsStyleRecalc();
+    clearChildNeedsStyleRecalc();
+    
+    if (hasCustomStyleCallbacks())
+        didRecalcStyle(change);
+    InspectorInstrumentation::didRecalculateStyleForElement(this);
+}
+
+ElementShadow* Element::shadow() const
+{
+    return hasRareData() ? elementRareData()->shadow() : 0;
+}
+
+ElementShadow* Element::ensureShadow()
+{
+    return ensureElementRareData()->ensureShadow();
+}
+
+void Element::didAffectSelector(AffectedSelectorMask mask)
+{
+    setNeedsStyleRecalc();
+    if (ElementShadow* elementShadow = shadowOfParentForDistribution(this))
+        elementShadow->didAffectSelector(mask);
+}
+
+PassRefPtr<ShadowRoot> Element::createShadowRoot(ExceptionCode& ec)
+{
+    if (alwaysCreateUserAgentShadowRoot())
+        ensureUserAgentShadowRoot();
+
+    if (RuntimeEnabledFeatures::authorShadowDOMForAnyElementEnabled())
+        return ensureShadow()->addShadowRoot(this, ShadowRoot::AuthorShadowRoot);
+
+    // Since some elements recreates shadow root dynamically, multiple shadow
+    // subtrees won't work well in that element. Until they are fixed, we disable
+    // adding author shadow root for them.
+    if (!areAuthorShadowsAllowed()) {
+        ec = HIERARCHY_REQUEST_ERR;
+        return 0;
+    }
+    return ensureShadow()->addShadowRoot(this, ShadowRoot::AuthorShadowRoot);
+}
+
+ShadowRoot* Element::shadowRoot() const
+{
+    ElementShadow* elementShadow = shadow();
+    if (!elementShadow)
+        return 0;
+    ShadowRoot* shadowRoot = elementShadow->youngestShadowRoot();
+    if (shadowRoot->type() == ShadowRoot::AuthorShadowRoot)
+        return shadowRoot;
+    return 0;
+}
+
+ShadowRoot* Element::userAgentShadowRoot() const
+{
+    if (ElementShadow* elementShadow = shadow()) {
+        if (ShadowRoot* shadowRoot = elementShadow->oldestShadowRoot()) {
+            ASSERT(shadowRoot->type() == ShadowRoot::UserAgentShadowRoot);
+            return shadowRoot;
+        }
+    }
+
+    return 0;
+}
+
+ShadowRoot* Element::ensureUserAgentShadowRoot()
+{
+    if (ShadowRoot* shadowRoot = userAgentShadowRoot())
+        return shadowRoot;
+    ShadowRoot* shadowRoot = ensureShadow()->addShadowRoot(this, ShadowRoot::UserAgentShadowRoot);
+    didAddUserAgentShadowRoot(shadowRoot);
+    return shadowRoot;
+}
+
+const AtomicString& Element::shadowPseudoId() const
+{
+    return pseudo();
+}
+
+bool Element::childTypeAllowed(NodeType type) const
+{
+    switch (type) {
+    case ELEMENT_NODE:
+    case TEXT_NODE:
+    case COMMENT_NODE:
+    case PROCESSING_INSTRUCTION_NODE:
+    case CDATA_SECTION_NODE:
+    case ENTITY_REFERENCE_NODE:
+        return true;
+    default:
+        break;
+    }
+    return false;
+}
+
+static void checkForEmptyStyleChange(Element* element, RenderStyle* style)
+{
+    if (!style && !element->styleAffectedByEmpty())
+        return;
+
+    if (!style || (element->styleAffectedByEmpty() && (!style->emptyState() || element->hasChildNodes())))
+        element->setNeedsStyleRecalc();
+}
+
+static void checkForSiblingStyleChanges(Element* e, RenderStyle* style, bool finishedParsingCallback,
+                                        Node* beforeChange, Node* afterChange, int childCountDelta)
+{
+    // :empty selector.
+    checkForEmptyStyleChange(e, style);
+    
+    if (!style || (e->needsStyleRecalc() && e->childrenAffectedByPositionalRules()))
+        return;
+
+    // :first-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
+    // In the DOM case, we only need to do something if |afterChange| is not 0.
+    // |afterChange| is 0 in the parser case, so it works out that we'll skip this block.
+    if (e->childrenAffectedByFirstChildRules() && afterChange) {
+        // Find our new first child.
+        Node* newFirstChild = 0;
+        for (newFirstChild = e->firstChild(); newFirstChild && !newFirstChild->isElementNode(); newFirstChild = newFirstChild->nextSibling()) {};
+        
+        // Find the first element node following |afterChange|
+        Node* firstElementAfterInsertion = 0;
+        for (firstElementAfterInsertion = afterChange;
+             firstElementAfterInsertion && !firstElementAfterInsertion->isElementNode();
+             firstElementAfterInsertion = firstElementAfterInsertion->nextSibling()) {};
+        
+        // This is the insert/append case.
+        if (newFirstChild != firstElementAfterInsertion && firstElementAfterInsertion && firstElementAfterInsertion->attached() &&
+            firstElementAfterInsertion->renderStyle() && firstElementAfterInsertion->renderStyle()->firstChildState())
+            firstElementAfterInsertion->setNeedsStyleRecalc();
+            
+        // We also have to handle node removal.
+        if (childCountDelta < 0 && newFirstChild == firstElementAfterInsertion && newFirstChild && (!newFirstChild->renderStyle() || !newFirstChild->renderStyle()->firstChildState()))
+            newFirstChild->setNeedsStyleRecalc();
+    }
+
+    // :last-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
+    // In the DOM case, we only need to do something if |afterChange| is not 0.
+    if (e->childrenAffectedByLastChildRules() && beforeChange) {
+        // Find our new last child.
+        Node* newLastChild = 0;
+        for (newLastChild = e->lastChild(); newLastChild && !newLastChild->isElementNode(); newLastChild = newLastChild->previousSibling()) {};
+        
+        // Find the last element node going backwards from |beforeChange|
+        Node* lastElementBeforeInsertion = 0;
+        for (lastElementBeforeInsertion = beforeChange;
+             lastElementBeforeInsertion && !lastElementBeforeInsertion->isElementNode();
+             lastElementBeforeInsertion = lastElementBeforeInsertion->previousSibling()) {};
+        
+        if (newLastChild != lastElementBeforeInsertion && lastElementBeforeInsertion && lastElementBeforeInsertion->attached() &&
+            lastElementBeforeInsertion->renderStyle() && lastElementBeforeInsertion->renderStyle()->lastChildState())
+            lastElementBeforeInsertion->setNeedsStyleRecalc();
+            
+        // We also have to handle node removal.  The parser callback case is similar to node removal as well in that we need to change the last child
+        // to match now.
+        if ((childCountDelta < 0 || finishedParsingCallback) && newLastChild == lastElementBeforeInsertion && newLastChild && (!newLastChild->renderStyle() || !newLastChild->renderStyle()->lastChildState()))
+            newLastChild->setNeedsStyleRecalc();
+    }
+
+    // The + selector.  We need to invalidate the first element following the insertion point.  It is the only possible element
+    // that could be affected by this DOM change.
+    if (e->childrenAffectedByDirectAdjacentRules() && afterChange) {
+        Node* firstElementAfterInsertion = 0;
+        for (firstElementAfterInsertion = afterChange;
+             firstElementAfterInsertion && !firstElementAfterInsertion->isElementNode();
+             firstElementAfterInsertion = firstElementAfterInsertion->nextSibling()) {};
+        if (firstElementAfterInsertion && firstElementAfterInsertion->attached())
+            firstElementAfterInsertion->setNeedsStyleRecalc();
+    }
+
+    // Forward positional selectors include the ~ selector, nth-child, nth-of-type, first-of-type and only-of-type.
+    // Backward positional selectors include nth-last-child, nth-last-of-type, last-of-type and only-of-type.
+    // We have to invalidate everything following the insertion point in the forward case, and everything before the insertion point in the
+    // backward case.
+    // |afterChange| is 0 in the parser callback case, so we won't do any work for the forward case if we don't have to.
+    // For performance reasons we just mark the parent node as changed, since we don't want to make childrenChanged O(n^2) by crawling all our kids
+    // here.  recalcStyle will then force a walk of the children when it sees that this has happened.
+    if ((e->childrenAffectedByForwardPositionalRules() && afterChange)
+        || (e->childrenAffectedByBackwardPositionalRules() && beforeChange))
+        e->setNeedsStyleRecalc();
+}
+
+void Element::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
+{
+    ContainerNode::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
+    if (changedByParser)
+        checkForEmptyStyleChange(this, renderStyle());
+    else
+        checkForSiblingStyleChanges(this, renderStyle(), false, beforeChange, afterChange, childCountDelta);
+
+    if (ElementShadow * shadow = this->shadow())
+        shadow->invalidateDistribution();
+}
+
+void Element::removeAllEventListeners()
+{
+    ContainerNode::removeAllEventListeners();
+    if (ElementShadow* shadow = this->shadow())
+        shadow->removeAllEventListeners();
+}
+
+void Element::beginParsingChildren()
+{
+    clearIsParsingChildrenFinished();
+    StyleResolver* styleResolver = document()->styleResolverIfExists();
+    if (styleResolver && attached())
+        styleResolver->pushParentElement(this);
+}
+
+void Element::finishParsingChildren()
+{
+    ContainerNode::finishParsingChildren();
+    setIsParsingChildrenFinished();
+    checkForSiblingStyleChanges(this, renderStyle(), true, lastChild(), 0, 0);
+    if (StyleResolver* styleResolver = document()->styleResolverIfExists())
+        styleResolver->popParentElement(this);
+}
+
+#ifndef NDEBUG
+void Element::formatForDebugger(char* buffer, unsigned length) const
+{
+    StringBuilder result;
+    String s;
+
+    result.append(nodeName());
+
+    s = getIdAttribute();
+    if (s.length() > 0) {
+        if (result.length() > 0)
+            result.appendLiteral("; ");
+        result.appendLiteral("id=");
+        result.append(s);
+    }
+
+    s = getAttribute(classAttr);
+    if (s.length() > 0) {
+        if (result.length() > 0)
+            result.appendLiteral("; ");
+        result.appendLiteral("class=");
+        result.append(s);
+    }
+
+    strncpy(buffer, result.toString().utf8().data(), length - 1);
+}
+#endif
+
+const Vector<RefPtr<Attr> >& Element::attrNodeList()
+{
+    ASSERT(hasSyntheticAttrChildNodes());
+    return *attrNodeListForElement(this);
+}
+
+PassRefPtr<Attr> Element::setAttributeNode(Attr* attrNode, ExceptionCode& ec)
+{
+    if (!attrNode) {
+        ec = TYPE_MISMATCH_ERR;
+        return 0;
+    }
+
+    RefPtr<Attr> oldAttrNode = attrIfExists(attrNode->qualifiedName());
+    if (oldAttrNode.get() == attrNode)
+        return attrNode; // This Attr is already attached to the element.
+
+    // INUSE_ATTRIBUTE_ERR: Raised if node is an Attr that is already an attribute of another Element object.
+    // The DOM user must explicitly clone Attr nodes to re-use them in other elements.
+    if (attrNode->ownerElement()) {
+        ec = INUSE_ATTRIBUTE_ERR;
+        return 0;
+    }
+
+    synchronizeAllAttributes();
+    UniqueElementData* elementData = ensureUniqueElementData();
+
+    size_t index = elementData->getAttributeItemIndex(attrNode->qualifiedName());
+    if (index != notFound) {
+        if (oldAttrNode)
+            detachAttrNodeFromElementWithValue(oldAttrNode.get(), elementData->attributeItem(index)->value());
+        else
+            oldAttrNode = Attr::create(document(), attrNode->qualifiedName(), elementData->attributeItem(index)->value());
+    }
+
+    setAttributeInternal(index, attrNode->qualifiedName(), attrNode->value(), NotInSynchronizationOfLazyAttribute);
+
+    attrNode->attachToElement(this);
+    ensureAttrNodeListForElement(this)->append(attrNode);
+
+    return oldAttrNode.release();
+}
+
+PassRefPtr<Attr> Element::setAttributeNodeNS(Attr* attr, ExceptionCode& ec)
+{
+    return setAttributeNode(attr, ec);
+}
+
+PassRefPtr<Attr> Element::removeAttributeNode(Attr* attr, ExceptionCode& ec)
+{
+    if (!attr) {
+        ec = TYPE_MISMATCH_ERR;
+        return 0;
+    }
+    if (attr->ownerElement() != this) {
+        ec = NOT_FOUND_ERR;
+        return 0;
+    }
+
+    ASSERT(document() == attr->document());
+
+    synchronizeAttribute(attr->qualifiedName());
+
+    size_t index = elementData()->getAttributeItemIndex(attr->qualifiedName());
+    if (index == notFound) {
+        ec = NOT_FOUND_ERR;
+        return 0;
+    }
+
+    return detachAttribute(index);
+}
+
+bool Element::parseAttributeName(QualifiedName& out, const AtomicString& namespaceURI, const AtomicString& qualifiedName, ExceptionCode& ec)
+{
+    String prefix, localName;
+    if (!Document::parseQualifiedName(qualifiedName, prefix, localName, ec))
+        return false;
+    ASSERT(!ec);
+
+    QualifiedName qName(prefix, localName, namespaceURI);
+
+    if (!Document::hasValidNamespaceForAttributes(qName)) {
+        ec = NAMESPACE_ERR;
+        return false;
+    }
+
+    out = qName;
+    return true;
+}
+
+void Element::setAttributeNS(const AtomicString& namespaceURI, const AtomicString& qualifiedName, const AtomicString& value, ExceptionCode& ec)
+{
+    QualifiedName parsedName = anyName;
+    if (!parseAttributeName(parsedName, namespaceURI, qualifiedName, ec))
+        return;
+    setAttribute(parsedName, value);
+}
+
+void Element::removeAttributeInternal(size_t index, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(index < attributeCount());
+
+    UniqueElementData* elementData = ensureUniqueElementData();
+
+    QualifiedName name = elementData->attributeItem(index)->name();
+    AtomicString valueBeingRemoved = elementData->attributeItem(index)->value();
+
+    if (!inSynchronizationOfLazyAttribute) {
+        if (!valueBeingRemoved.isNull())
+            willModifyAttribute(name, valueBeingRemoved, nullAtom);
+    }
+
+    if (RefPtr<Attr> attrNode = attrIfExists(name))
+        detachAttrNodeFromElementWithValue(attrNode.get(), elementData->attributeItem(index)->value());
+
+    elementData->removeAttribute(index);
+
+    if (!inSynchronizationOfLazyAttribute)
+        didRemoveAttribute(name);
+}
+
+void Element::addAttributeInternal(const QualifiedName& name, const AtomicString& value, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
+{
+    if (!inSynchronizationOfLazyAttribute)
+        willModifyAttribute(name, nullAtom, value);
+    ensureUniqueElementData()->addAttribute(name, value);
+    if (!inSynchronizationOfLazyAttribute)
+        didAddAttribute(name, value);
+}
+
+void Element::removeAttribute(const AtomicString& name)
+{
+    if (!elementData())
+        return;
+
+    AtomicString localName = shouldIgnoreAttributeCase(this) ? name.lower() : name;
+    size_t index = elementData()->getAttributeItemIndex(localName, false);
+    if (index == notFound) {
+        if (UNLIKELY(localName == styleAttr) && elementData()->m_styleAttributeIsDirty && isStyledElement())
+            static_cast<StyledElement*>(this)->removeAllInlineStyleProperties();
+        return;
+    }
+
+    removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
+}
+
+void Element::removeAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName)
+{
+    removeAttribute(QualifiedName(nullAtom, localName, namespaceURI));
+}
+
+PassRefPtr<Attr> Element::getAttributeNode(const AtomicString& localName)
+{
+    if (!elementData())
+        return 0;
+    synchronizeAttribute(localName);
+    const Attribute* attribute = elementData()->getAttributeItem(localName, shouldIgnoreAttributeCase(this));
+    if (!attribute)
+        return 0;
+    return ensureAttr(attribute->name());
+}
+
+PassRefPtr<Attr> Element::getAttributeNodeNS(const AtomicString& namespaceURI, const AtomicString& localName)
+{
+    if (!elementData())
+        return 0;
+    QualifiedName qName(nullAtom, localName, namespaceURI);
+    synchronizeAttribute(qName);
+    const Attribute* attribute = elementData()->getAttributeItem(qName);
+    if (!attribute)
+        return 0;
+    return ensureAttr(attribute->name());
+}
+
+bool Element::hasAttribute(const AtomicString& localName) const
+{
+    if (!elementData())
+        return false;
+    synchronizeAttribute(localName);
+    return elementData()->getAttributeItem(shouldIgnoreAttributeCase(this) ? localName.lower() : localName, false);
+}
+
+bool Element::hasAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName) const
+{
+    if (!elementData())
+        return false;
+    QualifiedName qName(nullAtom, localName, namespaceURI);
+    synchronizeAttribute(qName);
+    return elementData()->getAttributeItem(qName);
+}
+
+CSSStyleDeclaration *Element::style()
+{
+    return 0;
+}
+
+void Element::focus(bool restorePreviousSelection, FocusDirection direction)
+{
+    if (!inDocument())
+        return;
+
+    Document* doc = document();
+    if (doc->focusedNode() == this)
+        return;
+
+    // If the stylesheets have already been loaded we can reliably check isFocusable.
+    // If not, we continue and set the focused node on the focus controller below so
+    // that it can be updated soon after attach. 
+    if (doc->haveStylesheetsLoaded()) {
+        doc->updateLayoutIgnorePendingStylesheets();
+        if (!isFocusable())
+            return;
+    }
+
+    if (!supportsFocus())
+        return;
+
+    RefPtr<Node> protect;
+    if (Page* page = doc->page()) {
+        // Focus and change event handlers can cause us to lose our last ref.
+        // If a focus event handler changes the focus to a different node it
+        // does not make sense to continue and update appearence.
+        protect = this;
+        if (!page->focusController()->setFocusedNode(this, doc->frame(), direction))
+            return;
+    }
+
+    // Setting the focused node above might have invalidated the layout due to scripts.
+    doc->updateLayoutIgnorePendingStylesheets();
+
+    if (!isFocusable()) {
+        ensureElementRareData()->setNeedsFocusAppearanceUpdateSoonAfterAttach(true);
+        return;
+    }
+        
+    cancelFocusAppearanceUpdate();
+    updateFocusAppearance(restorePreviousSelection);
+}
+
+void Element::updateFocusAppearance(bool /*restorePreviousSelection*/)
+{
+    if (isRootEditableElement()) {
+        Frame* frame = document()->frame();
+        if (!frame)
+            return;
+        
+        // When focusing an editable element in an iframe, don't reset the selection if it already contains a selection.
+        if (this == frame->selection()->rootEditableElement())
+            return;
+
+        // FIXME: We should restore the previous selection if there is one.
+        VisibleSelection newSelection = VisibleSelection(firstPositionInOrBeforeNode(this), DOWNSTREAM);
+        
+        if (frame->selection()->shouldChangeSelection(newSelection)) {
+            frame->selection()->setSelection(newSelection);
+            frame->selection()->revealSelection();
+        }
+    } else if (renderer() && !renderer()->isWidget())
+        renderer()->scrollRectToVisible(boundingBox());
+}
+
+void Element::blur()
+{
+    cancelFocusAppearanceUpdate();
+    Document* doc = document();
+    if (treeScope()->focusedNode() == this) {
+        if (doc->frame())
+            doc->frame()->page()->focusController()->setFocusedNode(0, doc->frame());
+        else
+            doc->setFocusedNode(0);
+    }
+}
+
+String Element::innerText()
+{
+    // We need to update layout, since plainText uses line boxes in the render tree.
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    if (!renderer())
+        return textContent(true);
+
+    return plainText(rangeOfContents(const_cast<Element*>(this)).get());
+}
+
+String Element::outerText()
+{
+    // Getting outerText is the same as getting innerText, only
+    // setting is different. You would think this should get the plain
+    // text for the outer range, but this is wrong, <br> for instance
+    // would return different values for inner and outer text by such
+    // a rule, but it doesn't in WinIE, and we want to match that.
+    return innerText();
+}
+
+String Element::title() const
+{
+    return String();
+}
+
+const AtomicString& Element::pseudo() const
+{
+    return getAttribute(pseudoAttr);
+}
+
+void Element::setPseudo(const AtomicString& value)
+{
+    setAttribute(pseudoAttr, value);
+}
+
+LayoutSize Element::minimumSizeForResizing() const
+{
+    return hasRareData() ? elementRareData()->minimumSizeForResizing() : defaultMinimumSizeForResizing();
+}
+
+void Element::setMinimumSizeForResizing(const LayoutSize& size)
+{
+    if (!hasRareData() && size == defaultMinimumSizeForResizing())
+        return;
+    ensureElementRareData()->setMinimumSizeForResizing(size);
+}
+
+RenderStyle* Element::computedStyle(PseudoId pseudoElementSpecifier)
+{
+    if (PseudoElement* element = pseudoElement(pseudoElementSpecifier))
+        return element->computedStyle();
+
+    // FIXME: Find and use the renderer from the pseudo element instead of the actual element so that the 'length'
+    // properties, which are only known by the renderer because it did the layout, will be correct and so that the
+    // values returned for the ":selection" pseudo-element will be correct.
+    if (RenderStyle* usedStyle = renderStyle()) {
+        if (pseudoElementSpecifier) {
+            RenderStyle* cachedPseudoStyle = usedStyle->getCachedPseudoStyle(pseudoElementSpecifier);
+            return cachedPseudoStyle ? cachedPseudoStyle : usedStyle;
+         } else
+            return usedStyle;
+    }
+
+    if (!attached())
+        // FIXME: Try to do better than this. Ensure that styleForElement() works for elements that are not in the
+        // document tree and figure out when to destroy the computed style for such elements.
+        return 0;
+
+    ElementRareData* data = ensureElementRareData();
+    if (!data->computedStyle())
+        data->setComputedStyle(document()->styleForElementIgnoringPendingStylesheets(this));
+    return pseudoElementSpecifier ? data->computedStyle()->getCachedPseudoStyle(pseudoElementSpecifier) : data->computedStyle();
+}
+
+void Element::setStyleAffectedByEmpty()
+{
+    ensureElementRareData()->setStyleAffectedByEmpty(true);
+}
+
+void Element::setChildrenAffectedByHover(bool value)
+{
+    if (value || hasRareData())
+        ensureElementRareData()->setChildrenAffectedByHover(value);
+}
+
+void Element::setChildrenAffectedByActive(bool value)
+{
+    if (value || hasRareData())
+        ensureElementRareData()->setChildrenAffectedByActive(value);
+}
+
+void Element::setChildrenAffectedByDrag(bool value)
+{
+    if (value || hasRareData())
+        ensureElementRareData()->setChildrenAffectedByDrag(value);
+}
+
+void Element::setChildrenAffectedByFirstChildRules()
+{
+    ensureElementRareData()->setChildrenAffectedByFirstChildRules(true);
+}
+
+void Element::setChildrenAffectedByLastChildRules()
+{
+    ensureElementRareData()->setChildrenAffectedByLastChildRules(true);
+}
+
+void Element::setChildrenAffectedByDirectAdjacentRules()
+{
+    ensureElementRareData()->setChildrenAffectedByDirectAdjacentRules(true);
+}
+
+void Element::setChildrenAffectedByForwardPositionalRules()
+{
+    ensureElementRareData()->setChildrenAffectedByForwardPositionalRules(true);
+}
+
+void Element::setChildrenAffectedByBackwardPositionalRules()
+{
+    ensureElementRareData()->setChildrenAffectedByBackwardPositionalRules(true);
+}
+
+void Element::setChildIndex(unsigned index)
+{
+    ElementRareData* rareData = ensureElementRareData();
+    if (RenderStyle* style = renderStyle())
+        style->setUnique();
+    rareData->setChildIndex(index);
+}
+
+bool Element::hasFlagsSetDuringStylingOfChildren() const
+{
+    if (!hasRareData())
+        return false;
+    return rareDataChildrenAffectedByHover()
+        || rareDataChildrenAffectedByActive()
+        || rareDataChildrenAffectedByDrag()
+        || rareDataChildrenAffectedByFirstChildRules()
+        || rareDataChildrenAffectedByLastChildRules()
+        || rareDataChildrenAffectedByDirectAdjacentRules()
+        || rareDataChildrenAffectedByForwardPositionalRules()
+        || rareDataChildrenAffectedByBackwardPositionalRules();
+}
+
+bool Element::rareDataStyleAffectedByEmpty() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->styleAffectedByEmpty();
+}
+
+bool Element::rareDataChildrenAffectedByHover() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByHover();
+}
+
+bool Element::rareDataChildrenAffectedByActive() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByActive();
+}
+
+bool Element::rareDataChildrenAffectedByDrag() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByDrag();
+}
+
+bool Element::rareDataChildrenAffectedByFirstChildRules() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByFirstChildRules();
+}
+
+bool Element::rareDataChildrenAffectedByLastChildRules() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByLastChildRules();
+}
+
+bool Element::rareDataChildrenAffectedByDirectAdjacentRules() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByDirectAdjacentRules();
+}
+
+bool Element::rareDataChildrenAffectedByForwardPositionalRules() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByForwardPositionalRules();
+}
+
+bool Element::rareDataChildrenAffectedByBackwardPositionalRules() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childrenAffectedByBackwardPositionalRules();
+}
+
+unsigned Element::rareDataChildIndex() const
+{
+    ASSERT(hasRareData());
+    return elementRareData()->childIndex();
+}
+
+void Element::setIsInCanvasSubtree(bool isInCanvasSubtree)
+{
+    ensureElementRareData()->setIsInCanvasSubtree(isInCanvasSubtree);
+}
+
+bool Element::isInCanvasSubtree() const
+{
+    return hasRareData() && elementRareData()->isInCanvasSubtree();
+}
+
+bool Element::isUnresolvedCustomElement()
+{
+    return isCustomElement() && document()->registry()->isUnresolved(this);
+}
+
+AtomicString Element::computeInheritedLanguage() const
+{
+    const Node* n = this;
+    AtomicString value;
+    // The language property is inherited, so we iterate over the parents to find the first language.
+    do {
+        if (n->isElementNode()) {
+            if (const ElementData* elementData = toElement(n)->elementData()) {
+                // Spec: xml:lang takes precedence -- http://www.w3.org/TR/xhtml1/#C_7
+                if (const Attribute* attribute = elementData->getAttributeItem(XMLNames::langAttr))
+                    value = attribute->value();
+                else if (const Attribute* attribute = elementData->getAttributeItem(HTMLNames::langAttr))
+                    value = attribute->value();
+            }
+        } else if (n->isDocumentNode()) {
+            // checking the MIME content-language
+            value = toDocument(n)->contentLanguage();
+        }
+
+        n = n->parentNode();
+    } while (n && value.isNull());
+
+    return value;
+}
+
+Locale& Element::locale() const
+{
+    return document()->getCachedLocale(computeInheritedLanguage());
+}
+
+void Element::cancelFocusAppearanceUpdate()
+{
+    if (hasRareData())
+        elementRareData()->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
+    if (document()->focusedNode() == this)
+        document()->cancelFocusAppearanceUpdate();
+}
+
+void Element::normalizeAttributes()
+{
+    if (!hasAttributes())
+        return;
+    for (unsigned i = 0; i < attributeCount(); ++i) {
+        if (RefPtr<Attr> attr = attrIfExists(attributeItem(i)->name()))
+            attr->normalize();
+    }
+}
+
+void Element::updatePseudoElement(PseudoId pseudoId, StyleChange change)
+{
+    PseudoElement* element = pseudoElement(pseudoId);
+    if (element && (needsStyleRecalc() || shouldRecalcStyle(change, element))) {
+        // PseudoElement styles hang off their parent element's style so if we needed
+        // a style recalc we should Force one on the pseudo.
+        element->recalcStyle(needsStyleRecalc() ? Force : change);
+
+        // Wait until our parent is not displayed or pseudoElementRendererIsNeeded
+        // is false, otherwise we could continously create and destroy PseudoElements
+        // when RenderObject::isChildAllowed on our parent returns false for the
+        // PseudoElement's renderer for each style recalc.
+        if (!renderer() || !pseudoElementRendererIsNeeded(renderer()->getCachedPseudoStyle(pseudoId)))
+            setPseudoElement(pseudoId, 0);
+    } else if (change >= Inherit || needsStyleRecalc())
+        createPseudoElementIfNeeded(pseudoId);
+}
+
+void Element::createPseudoElementIfNeeded(PseudoId pseudoId)
+{
+    if (!document()->styleSheetCollection()->usesBeforeAfterRules())
+        return;
+
+    if (!renderer() || !pseudoElementRendererIsNeeded(renderer()->getCachedPseudoStyle(pseudoId)))
+        return;
+
+    if (!renderer()->canHaveGeneratedChildren())
+        return;
+
+    ASSERT(!isPseudoElement());
+    RefPtr<PseudoElement> element = PseudoElement::create(this, pseudoId);
+    element->attach();
+    setPseudoElement(pseudoId, element.release());
+}
+
+bool Element::hasPseudoElements() const
+{
+    return hasRareData() && elementRareData()->hasPseudoElements();
+}
+
+PseudoElement* Element::pseudoElement(PseudoId pseudoId) const
+{
+    return hasRareData() ? elementRareData()->pseudoElement(pseudoId) : 0;
+}
+
+void Element::setPseudoElement(PseudoId pseudoId, PassRefPtr<PseudoElement> element)
+{
+    ensureElementRareData()->setPseudoElement(pseudoId, element);
+    resetNeedsShadowTreeWalker();
+}
+
+RenderObject* Element::pseudoElementRenderer(PseudoId pseudoId) const
+{
+    if (PseudoElement* element = pseudoElement(pseudoId))
+        return element->renderer();
+    return 0;
+}
+
+// ElementTraversal API
+Element* Element::firstElementChild() const
+{
+    return ElementTraversal::firstWithin(this);
+}
+
+Element* Element::lastElementChild() const
+{
+    Node* n = lastChild();
+    while (n && !n->isElementNode())
+        n = n->previousSibling();
+    return toElement(n);
+}
+
+unsigned Element::childElementCount() const
+{
+    unsigned count = 0;
+    Node* n = firstChild();
+    while (n) {
+        count += n->isElementNode();
+        n = n->nextSibling();
+    }
+    return count;
+}
+
+bool Element::matchesReadOnlyPseudoClass() const
+{
+    return false;
+}
+
+bool Element::matchesReadWritePseudoClass() const
+{
+    return false;
+}
+
+bool Element::webkitMatchesSelector(const String& selector, ExceptionCode& ec)
+{
+    if (selector.isEmpty()) {
+        ec = SYNTAX_ERR;
+        return false;
+    }
+
+    SelectorQuery* selectorQuery = document()->selectorQueryCache()->add(selector, document(), ec);
+    if (!selectorQuery)
+        return false;
+    return selectorQuery->matches(this);
+}
+
+bool Element::shouldAppearIndeterminate() const
+{
+    return false;
+}
+
+DOMTokenList* Element::classList()
+{
+    ElementRareData* data = ensureElementRareData();
+    if (!data->classList())
+        data->setClassList(ClassList::create(this));
+    return data->classList();
+}
+
+DOMStringMap* Element::dataset()
+{
+    ElementRareData* data = ensureElementRareData();
+    if (!data->dataset())
+        data->setDataset(DatasetDOMStringMap::create(this));
+    return data->dataset();
+}
+
+KURL Element::getURLAttribute(const QualifiedName& name) const
+{
+#if !ASSERT_DISABLED
+    if (elementData()) {
+        if (const Attribute* attribute = getAttributeItem(name))
+            ASSERT(isURLAttribute(*attribute));
+    }
+#endif
+    return document()->completeURL(stripLeadingAndTrailingHTMLSpaces(getAttribute(name)));
+}
+
+KURL Element::getNonEmptyURLAttribute(const QualifiedName& name) const
+{
+#if !ASSERT_DISABLED
+    if (elementData()) {
+        if (const Attribute* attribute = getAttributeItem(name))
+            ASSERT(isURLAttribute(*attribute));
+    }
+#endif
+    String value = stripLeadingAndTrailingHTMLSpaces(getAttribute(name));
+    if (value.isEmpty())
+        return KURL();
+    return document()->completeURL(value);
+}
+
+int Element::getIntegralAttribute(const QualifiedName& attributeName) const
+{
+    return getAttribute(attributeName).string().toInt();
+}
+
+void Element::setIntegralAttribute(const QualifiedName& attributeName, int value)
+{
+    // FIXME: Need an AtomicString version of String::number.
+    setAttribute(attributeName, String::number(value));
+}
+
+unsigned Element::getUnsignedIntegralAttribute(const QualifiedName& attributeName) const
+{
+    return getAttribute(attributeName).string().toUInt();
+}
+
+void Element::setUnsignedIntegralAttribute(const QualifiedName& attributeName, unsigned value)
+{
+    // FIXME: Need an AtomicString version of String::number.
+    setAttribute(attributeName, String::number(value));
+}
+
+#if ENABLE(SVG)
+bool Element::childShouldCreateRenderer(const NodeRenderingContext& childContext) const
+{
+    // Only create renderers for SVG elements whose parents are SVG elements, or for proper <svg xmlns="svgNS"> subdocuments.
+    if (childContext.node()->isSVGElement())
+        return childContext.node()->hasTagName(SVGNames::svgTag) || isSVGElement();
+
+    return ContainerNode::childShouldCreateRenderer(childContext);
+}
+#endif
+
+void Element::webkitRequestFullscreen()
+{
+    document()->requestFullScreenForElement(this, ALLOW_KEYBOARD_INPUT, Document::EnforceIFrameAllowFullScreenRequirement);
+}
+
+void Element::webkitRequestFullScreen(unsigned short flags)
+{
+    document()->requestFullScreenForElement(this, (flags | LEGACY_MOZILLA_REQUEST), Document::EnforceIFrameAllowFullScreenRequirement);
+}
+
+bool Element::containsFullScreenElement() const
+{
+    return hasRareData() && elementRareData()->containsFullScreenElement();
+}
+
+void Element::setContainsFullScreenElement(bool flag)
+{
+    ensureElementRareData()->setContainsFullScreenElement(flag);
+    setNeedsStyleRecalc(SyntheticStyleChange);
+}
+
+static Element* parentCrossingFrameBoundaries(Element* element)
+{
+    ASSERT(element);
+    return element->parentElement() ? element->parentElement() : element->document()->ownerElement();
+}
+
+void Element::setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(bool flag)
+{
+    Element* element = this;
+    while ((element = parentCrossingFrameBoundaries(element)))
+        element->setContainsFullScreenElement(flag);
+}
+
+bool Element::isInTopLayer() const
+{
+    return hasRareData() && elementRareData()->isInTopLayer();
+}
+
+void Element::setIsInTopLayer(bool inTopLayer)
+{
+    if (isInTopLayer() == inTopLayer)
+        return;
+    ensureElementRareData()->setIsInTopLayer(inTopLayer);
+
+    // We must ensure a reattach occurs so the renderer is inserted in the correct sibling order under RenderView according to its
+    // top layer position, or in its usual place if not in the top layer.
+    reattachIfAttached();
+}
+
+void Element::webkitRequestPointerLock()
+{
+    if (document()->page())
+        document()->page()->pointerLockController()->requestPointerLock(this);
+}
+
+SpellcheckAttributeState Element::spellcheckAttributeState() const
+{
+    const AtomicString& value = getAttribute(HTMLNames::spellcheckAttr);
+    if (value == nullAtom)
+        return SpellcheckAttributeDefault;
+    if (equalIgnoringCase(value, "true") || equalIgnoringCase(value, ""))
+        return SpellcheckAttributeTrue;
+    if (equalIgnoringCase(value, "false"))
+        return SpellcheckAttributeFalse;
+
+    return SpellcheckAttributeDefault;
+}
+
+bool Element::isSpellCheckingEnabled() const
+{
+    for (const Element* element = this; element; element = element->parentOrShadowHostElement()) {
+        switch (element->spellcheckAttributeState()) {
+        case SpellcheckAttributeTrue:
+            return true;
+        case SpellcheckAttributeFalse:
+            return false;
+        case SpellcheckAttributeDefault:
+            break;
+        }
+    }
+
+    return true;
+}
+
+RenderRegion* Element::renderRegion() const
+{
+    if (renderer() && renderer()->isRenderRegion())
+        return toRenderRegion(renderer());
+
+    return 0;
+}
+
+const AtomicString& Element::webkitRegionOverset() const
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    DEFINE_STATIC_LOCAL(AtomicString, undefinedState, ("undefined", AtomicString::ConstructFromLiteral));
+    if (!RuntimeEnabledFeatures::cssRegionsEnabled() || !renderRegion())
+        return undefinedState;
+
+    switch (renderRegion()->regionState()) {
+    case RenderRegion::RegionFit: {
+        DEFINE_STATIC_LOCAL(AtomicString, fitState, ("fit", AtomicString::ConstructFromLiteral));
+        return fitState;
+    }
+    case RenderRegion::RegionEmpty: {
+        DEFINE_STATIC_LOCAL(AtomicString, emptyState, ("empty", AtomicString::ConstructFromLiteral));
+        return emptyState;
+    }
+    case RenderRegion::RegionOverset: {
+        DEFINE_STATIC_LOCAL(AtomicString, overflowState, ("overset", AtomicString::ConstructFromLiteral));
+        return overflowState;
+    }
+    case RenderRegion::RegionUndefined:
+        return undefinedState;
+    }
+
+    ASSERT_NOT_REACHED();
+    return undefinedState;
+}
+
+Vector<RefPtr<Range> > Element::webkitGetRegionFlowRanges() const
+{
+    document()->updateLayoutIgnorePendingStylesheets();
+
+    Vector<RefPtr<Range> > rangeObjects;
+    if (RuntimeEnabledFeatures::cssRegionsEnabled() && renderer() && renderer()->isRenderRegion()) {
+        RenderRegion* region = toRenderRegion(renderer());
+        if (region->isValid())
+            region->getRanges(rangeObjects);
+    }
+
+    return rangeObjects;
+}
+
+#ifndef NDEBUG
+bool Element::fastAttributeLookupAllowed(const QualifiedName& name) const
+{
+    if (name == HTMLNames::styleAttr)
+        return false;
+
+#if ENABLE(SVG)
+    if (isSVGElement())
+        return !static_cast<const SVGElement*>(this)->isAnimatableAttribute(name);
+#endif
+
+    return true;
+}
+#endif
+
+#ifdef DUMP_NODE_STATISTICS
+bool Element::hasNamedNodeMap() const
+{
+    return hasRareData() && elementRareData()->attributeMap();
+}
+#endif
+
+inline void Element::updateName(const AtomicString& oldName, const AtomicString& newName)
+{
+    if (!inDocument() || isInShadowTree())
+        return;
+
+    if (oldName == newName)
+        return;
+
+    if (shouldRegisterAsNamedItem())
+        updateNamedItemRegistration(oldName, newName);
+}
+
+inline void Element::updateId(const AtomicString& oldId, const AtomicString& newId)
+{
+    if (!isInTreeScope())
+        return;
+
+    if (oldId == newId)
+        return;
+
+    updateId(treeScope(), oldId, newId);
+}
+
+inline void Element::updateId(TreeScope* scope, const AtomicString& oldId, const AtomicString& newId)
+{
+    ASSERT(isInTreeScope());
+    ASSERT(oldId != newId);
+
+    if (!oldId.isEmpty())
+        scope->removeElementById(oldId, this);
+    if (!newId.isEmpty())
+        scope->addElementById(newId, this);
+
+    if (shouldRegisterAsExtraNamedItem())
+        updateExtraNamedItemRegistration(oldId, newId);
+}
+
+void Element::updateLabel(TreeScope* scope, const AtomicString& oldForAttributeValue, const AtomicString& newForAttributeValue)
+{
+    ASSERT(hasTagName(labelTag));
+
+    if (!inDocument())
+        return;
+
+    if (oldForAttributeValue == newForAttributeValue)
+        return;
+
+    if (!oldForAttributeValue.isEmpty())
+        scope->removeLabel(oldForAttributeValue, static_cast<HTMLLabelElement*>(this));
+    if (!newForAttributeValue.isEmpty())
+        scope->addLabel(newForAttributeValue, static_cast<HTMLLabelElement*>(this));
+}
+
+void Element::willModifyAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
+{
+    if (isIdAttributeName(name))
+        updateId(oldValue, newValue);
+    else if (name == HTMLNames::nameAttr)
+        updateName(oldValue, newValue);
+    else if (name == HTMLNames::forAttr && hasTagName(labelTag)) {
+        TreeScope* scope = treeScope();
+        if (scope->shouldCacheLabelsByForAttribute())
+            updateLabel(scope, oldValue, newValue);
+    }
+
+    if (oldValue != newValue) {
+        if (attached() && document()->styleResolver() && document()->styleResolver()->hasSelectorForAttribute(name.localName()))
+           setNeedsStyleRecalc();
+    }
+
+    if (OwnPtr<MutationObserverInterestGroup> recipients = MutationObserverInterestGroup::createForAttributesMutation(this, name))
+        recipients->enqueueMutationRecord(MutationRecord::createAttributes(this, name, oldValue));
+
+    InspectorInstrumentation::willModifyDOMAttr(document(), this, oldValue, newValue);
+}
+
+void Element::didAddAttribute(const QualifiedName& name, const AtomicString& value)
+{
+    attributeChanged(name, value);
+    InspectorInstrumentation::didModifyDOMAttr(document(), this, name.localName(), value);
+    dispatchSubtreeModifiedEvent();
+}
+
+void Element::didModifyAttribute(const QualifiedName& name, const AtomicString& value)
+{
+    attributeChanged(name, value);
+    InspectorInstrumentation::didModifyDOMAttr(document(), this, name.localName(), value);
+    // Do not dispatch a DOMSubtreeModified event here; see bug 81141.
+}
+
+void Element::didRemoveAttribute(const QualifiedName& name)
+{
+    attributeChanged(name, nullAtom);
+    InspectorInstrumentation::didRemoveDOMAttr(document(), this, name.localName());
+    dispatchSubtreeModifiedEvent();
+}
+
+
+void Element::updateNamedItemRegistration(const AtomicString& oldName, const AtomicString& newName)
+{
+    if (!document()->isHTMLDocument())
+        return;
+
+    if (!oldName.isEmpty())
+        toHTMLDocument(document())->removeNamedItem(oldName);
+
+    if (!newName.isEmpty())
+        toHTMLDocument(document())->addNamedItem(newName);
+}
+
+void Element::updateExtraNamedItemRegistration(const AtomicString& oldId, const AtomicString& newId)
+{
+    if (!document()->isHTMLDocument())
+        return;
+
+    if (!oldId.isEmpty())
+        toHTMLDocument(document())->removeExtraNamedItem(oldId);
+
+    if (!newId.isEmpty())
+        toHTMLDocument(document())->addExtraNamedItem(newId);
+}
+
+PassRefPtr<HTMLCollection> Element::ensureCachedHTMLCollection(CollectionType type)
+{
+    if (HTMLCollection* collection = cachedHTMLCollection(type))
+        return collection;
+
+    RefPtr<HTMLCollection> collection;
+    if (type == TableRows) {
+        ASSERT(hasTagName(tableTag));
+        return ensureRareData()->ensureNodeLists()->addCacheWithAtomicName<HTMLTableRowsCollection>(this, type);
+    } else if (type == SelectOptions) {
+        ASSERT(hasTagName(selectTag));
+        return ensureRareData()->ensureNodeLists()->addCacheWithAtomicName<HTMLOptionsCollection>(this, type);
+    } else if (type == FormControls) {
+        ASSERT(hasTagName(formTag) || hasTagName(fieldsetTag));
+        return ensureRareData()->ensureNodeLists()->addCacheWithAtomicName<HTMLFormControlsCollection>(this, type);
+    }
+    return ensureRareData()->ensureNodeLists()->addCacheWithAtomicName<HTMLCollection>(this, type);
+}
+
+HTMLCollection* Element::cachedHTMLCollection(CollectionType type)
+{
+    return hasRareData() && rareData()->nodeLists() ? rareData()->nodeLists()->cacheWithAtomicName<HTMLCollection>(type) : 0;
+}
+
+IntSize Element::savedLayerScrollOffset() const
+{
+    return hasRareData() ? elementRareData()->savedLayerScrollOffset() : IntSize();
+}
+
+void Element::setSavedLayerScrollOffset(const IntSize& size)
+{
+    if (size.isZero() && !hasRareData())
+        return;
+    ensureElementRareData()->setSavedLayerScrollOffset(size);
+}
+
+PassRefPtr<Attr> Element::attrIfExists(const QualifiedName& name)
+{
+    if (AttrNodeList* attrNodeList = attrNodeListForElement(this))
+        return findAttrNodeInList(attrNodeList, name);
+    return 0;
+}
+
+PassRefPtr<Attr> Element::ensureAttr(const QualifiedName& name)
+{
+    AttrNodeList* attrNodeList = ensureAttrNodeListForElement(this);
+    RefPtr<Attr> attrNode = findAttrNodeInList(attrNodeList, name);
+    if (!attrNode) {
+        attrNode = Attr::create(this, name);
+        treeScope()->adoptIfNeeded(attrNode.get());
+        attrNodeList->append(attrNode);
+    }
+    return attrNode.release();
+}
+
+void Element::detachAttrNodeFromElementWithValue(Attr* attrNode, const AtomicString& value)
+{
+    ASSERT(hasSyntheticAttrChildNodes());
+    attrNode->detachFromElementWithValue(value);
+
+    AttrNodeList* attrNodeList = attrNodeListForElement(this);
+    for (unsigned i = 0; i < attrNodeList->size(); ++i) {
+        if (attrNodeList->at(i)->qualifiedName() == attrNode->qualifiedName()) {
+            attrNodeList->remove(i);
+            if (attrNodeList->isEmpty())
+                removeAttrNodeListForElement(this);
+            return;
+        }
+    }
+    ASSERT_NOT_REACHED();
+}
+
+void Element::detachAllAttrNodesFromElement()
+{
+    AttrNodeList* attrNodeList = attrNodeListForElement(this);
+    ASSERT(attrNodeList);
+
+    for (unsigned i = 0; i < attributeCount(); ++i) {
+        const Attribute* attribute = attributeItem(i);
+        if (RefPtr<Attr> attrNode = findAttrNodeInList(attrNodeList, attribute->name()))
+            attrNode->detachFromElementWithValue(attribute->value());
+    }
+
+    removeAttrNodeListForElement(this);
+}
+
+void Element::willRecalcStyle(StyleChange)
+{
+    ASSERT(hasCustomStyleCallbacks());
+}
+
+void Element::didRecalcStyle(StyleChange)
+{
+    ASSERT(hasCustomStyleCallbacks());
+}
+
+
+PassRefPtr<RenderStyle> Element::customStyleForRenderer()
+{
+    ASSERT(hasCustomStyleCallbacks());
+    return 0;
+}
+
+void Element::cloneAttributesFromElement(const Element& other)
+{
+    if (hasSyntheticAttrChildNodes())
+        detachAllAttrNodesFromElement();
+
+    other.synchronizeAllAttributes();
+    if (!other.m_elementData) {
+        m_elementData.clear();
+        return;
+    }
+
+    const AtomicString& oldID = getIdAttribute();
+    const AtomicString& newID = other.getIdAttribute();
+
+    if (!oldID.isNull() || !newID.isNull())
+        updateId(oldID, newID);
+
+    const AtomicString& oldName = getNameAttribute();
+    const AtomicString& newName = other.getNameAttribute();
+
+    if (!oldName.isNull() || !newName.isNull())
+        updateName(oldName, newName);
+
+    // If 'other' has a mutable ElementData, convert it to an immutable one so we can share it between both elements.
+    // We can only do this if there is no CSSOM wrapper for other's inline style, and there are no presentation attributes.
+    if (other.m_elementData->isUnique()
+        && !other.m_elementData->presentationAttributeStyle()
+        && (!other.m_elementData->inlineStyle() || !other.m_elementData->inlineStyle()->hasCSSOMWrapper()))
+        const_cast<Element&>(other).m_elementData = static_cast<const UniqueElementData*>(other.m_elementData.get())->makeShareableCopy();
+
+    if (!other.m_elementData->isUnique())
+        m_elementData = other.m_elementData;
+    else
+        m_elementData = other.m_elementData->makeUniqueCopy();
+
+    for (unsigned i = 0; i < m_elementData->length(); ++i) {
+        const Attribute* attribute = const_cast<const ElementData*>(m_elementData.get())->attributeItem(i);
+        attributeChangedFromParserOrByCloning(attribute->name(), attribute->value(), ModifiedByCloning);
+    }
+}
+
+void Element::cloneDataFromElement(const Element& other)
+{
+    cloneAttributesFromElement(other);
+    copyNonAttributePropertiesFromElement(other);
+}
+
+void Element::createUniqueElementData()
+{
+    if (!m_elementData)
+        m_elementData = UniqueElementData::create();
+    else {
+        ASSERT(!m_elementData->isUnique());
+        m_elementData = static_cast<ShareableElementData*>(m_elementData.get())->makeUniqueCopy();
+    }
+}
+
+void Element::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
+{
+    MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::DOM);
+    ContainerNode::reportMemoryUsage(memoryObjectInfo);
+    info.addMember(m_tagName, "tagName");
+    info.addMember(m_elementData, "elementData");
+}
+
+#if ENABLE(SVG)
+bool Element::hasPendingResources() const
+{
+    return hasRareData() && elementRareData()->hasPendingResources();
+}
+
+void Element::setHasPendingResources()
+{
+    ensureElementRareData()->setHasPendingResources(true);
+}
+
+void Element::clearHasPendingResources()
+{
+    ensureElementRareData()->setHasPendingResources(false);
+}
+#endif
+
+void ElementData::deref()
+{
+    if (!derefBase())
+        return;
+
+    if (m_isUnique)
+        delete static_cast<UniqueElementData*>(this);
+    else
+        delete static_cast<ShareableElementData*>(this);
+}
+
+ElementData::ElementData()
+    : m_isUnique(true)
+    , m_arraySize(0)
+    , m_presentationAttributeStyleIsDirty(false)
+    , m_styleAttributeIsDirty(false)
+#if ENABLE(SVG)
+    , m_animatedSVGAttributesAreDirty(false)
+#endif
+{
+}
+
+ElementData::ElementData(unsigned arraySize)
+    : m_isUnique(false)
+    , m_arraySize(arraySize)
+    , m_presentationAttributeStyleIsDirty(false)
+    , m_styleAttributeIsDirty(false)
+#if ENABLE(SVG)
+    , m_animatedSVGAttributesAreDirty(false)
+#endif
+{
+}
+
+struct SameSizeAsElementData : public RefCounted<SameSizeAsElementData> {
+    unsigned bitfield;
+    void* refPtrs[3];
+};
+
+COMPILE_ASSERT(sizeof(ElementData) == sizeof(SameSizeAsElementData), element_attribute_data_should_stay_small);
+
+static size_t sizeForShareableElementDataWithAttributeCount(unsigned count)
+{
+    return sizeof(ShareableElementData) + sizeof(Attribute) * count;
+}
+
+PassRefPtr<ShareableElementData> ShareableElementData::createWithAttributes(const Vector<Attribute>& attributes)
+{
+    void* slot = WTF::fastMalloc(sizeForShareableElementDataWithAttributeCount(attributes.size()));
+    return adoptRef(new (slot) ShareableElementData(attributes));
+}
+
+PassRefPtr<UniqueElementData> UniqueElementData::create()
+{
+    return adoptRef(new UniqueElementData);
+}
+
+ShareableElementData::ShareableElementData(const Vector<Attribute>& attributes)
+    : ElementData(attributes.size())
+{
+    for (unsigned i = 0; i < m_arraySize; ++i)
+        new (&m_attributeArray[i]) Attribute(attributes[i]);
+}
+
+ShareableElementData::~ShareableElementData()
+{
+    for (unsigned i = 0; i < m_arraySize; ++i)
+        m_attributeArray[i].~Attribute();
+}
+
+ShareableElementData::ShareableElementData(const UniqueElementData& other)
+    : ElementData(other, false)
+{
+    ASSERT(!other.m_presentationAttributeStyle);
+
+    if (other.m_inlineStyle) {
+        ASSERT(!other.m_inlineStyle->hasCSSOMWrapper());
+        m_inlineStyle = other.m_inlineStyle->immutableCopyIfNeeded();
+    }
+
+    for (unsigned i = 0; i < m_arraySize; ++i)
+        new (&m_attributeArray[i]) Attribute(other.m_attributeVector.at(i));
+}
+
+ElementData::ElementData(const ElementData& other, bool isUnique)
+    : m_isUnique(isUnique)
+    , m_arraySize(isUnique ? 0 : other.length())
+    , m_presentationAttributeStyleIsDirty(other.m_presentationAttributeStyleIsDirty)
+    , m_styleAttributeIsDirty(other.m_styleAttributeIsDirty)
+#if ENABLE(SVG)
+    , m_animatedSVGAttributesAreDirty(other.m_animatedSVGAttributesAreDirty)
+#endif
+    , m_classNames(other.m_classNames)
+    , m_idForStyleResolution(other.m_idForStyleResolution)
+{
+    // NOTE: The inline style is copied by the subclass copy constructor since we don't know what to do with it here.
+}
+
+UniqueElementData::UniqueElementData()
+{
+}
+
+UniqueElementData::UniqueElementData(const UniqueElementData& other)
+    : ElementData(other, true)
+    , m_presentationAttributeStyle(other.m_presentationAttributeStyle)
+    , m_attributeVector(other.m_attributeVector)
+{
+    m_inlineStyle = other.m_inlineStyle ? other.m_inlineStyle->copy() : 0;
+}
+
+UniqueElementData::UniqueElementData(const ShareableElementData& other)
+    : ElementData(other, true)
+{
+    // An ShareableElementData should never have a mutable inline StylePropertySet attached.
+    ASSERT(!other.m_inlineStyle || !other.m_inlineStyle->isMutable());
+    m_inlineStyle = other.m_inlineStyle;
+
+    m_attributeVector.reserveCapacity(other.length());
+    for (unsigned i = 0; i < other.length(); ++i)
+        m_attributeVector.uncheckedAppend(other.m_attributeArray[i]);
+}
+
+PassRefPtr<UniqueElementData> ElementData::makeUniqueCopy() const
+{
+    if (isUnique())
+        return adoptRef(new UniqueElementData(static_cast<const UniqueElementData&>(*this)));
+    return adoptRef(new UniqueElementData(static_cast<const ShareableElementData&>(*this)));
+}
+
+PassRefPtr<ShareableElementData> UniqueElementData::makeShareableCopy() const
+{
+    void* slot = WTF::fastMalloc(sizeForShareableElementDataWithAttributeCount(m_attributeVector.size()));
+    return adoptRef(new (slot) ShareableElementData(*this));
+}
+
+void UniqueElementData::addAttribute(const QualifiedName& attributeName, const AtomicString& value)
+{
+    m_attributeVector.append(Attribute(attributeName, value));
+}
+
+void UniqueElementData::removeAttribute(size_t index)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(index < length());
+    m_attributeVector.remove(index);
+}
+
+bool ElementData::isEquivalent(const ElementData* other) const
+{
+    if (!other)
+        return isEmpty();
+
+    unsigned len = length();
+    if (len != other->length())
+        return false;
+
+    for (unsigned i = 0; i < len; i++) {
+        const Attribute* attribute = attributeItem(i);
+        const Attribute* otherAttr = other->getAttributeItem(attribute->name());
+        if (!otherAttr || attribute->value() != otherAttr->value())
+            return false;
+    }
+
+    return true;
+}
+
+void ElementData::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
+{
+    size_t actualSize = m_isUnique ? sizeof(ElementData) : sizeForShareableElementDataWithAttributeCount(m_arraySize);
+    MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::DOM, actualSize);
+    info.addMember(m_inlineStyle, "inlineStyle");
+    info.addMember(m_classNames, "classNames");
+    info.addMember(m_idForStyleResolution, "idForStyleResolution");
+    if (m_isUnique) {
+        const UniqueElementData* uniqueThis = static_cast<const UniqueElementData*>(this);
+        info.addMember(uniqueThis->m_presentationAttributeStyle, "presentationAttributeStyle");
+        info.addMember(uniqueThis->m_attributeVector, "attributeVector");
+    }
+    for (unsigned i = 0, len = length(); i < len; i++)
+        info.addMember(*attributeItem(i), "*attributeItem");
+}
+
+size_t ElementData::getAttributeItemIndexSlowCase(const AtomicString& name, bool shouldIgnoreAttributeCase) const
+{
+    // Continue to checking case-insensitively and/or full namespaced names if necessary:
+    for (unsigned i = 0; i < length(); ++i) {
+        const Attribute* attribute = attributeItem(i);
+        if (!attribute->name().hasPrefix()) {
+            if (shouldIgnoreAttributeCase && equalIgnoringCase(name, attribute->localName()))
+                return i;
+        } else {
+            // FIXME: Would be faster to do this comparison without calling toString, which
+            // generates a temporary string by concatenation. But this branch is only reached
+            // if the attribute name has a prefix, which is rare in HTML.
+            if (equalPossiblyIgnoringCase(name, attribute->name().toString(), shouldIgnoreAttributeCase))
+                return i;
+        }
+    }
+    return notFound;
+}
+
+Attribute* UniqueElementData::getAttributeItem(const QualifiedName& name)
+{
+    for (unsigned i = 0; i < length(); ++i) {
+        if (m_attributeVector.at(i).name().matches(name))
+            return &m_attributeVector.at(i);
+    }
+    return 0;
+}
+
+Attribute* UniqueElementData::attributeItem(unsigned index)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(index < length());
+    return &m_attributeVector.at(index);
+}
+
+} // namespace WebCore