Use Document, rather than document element, for implicit root.

third_party/WebKit/Source/core/dom/Element.h

 /*
  * 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)
  * Copyright (C) 2003-2011, 2013, 2014 Apple Inc. All rights reserved.
  *
  * 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
@@ skipping 34 matching lines @@
 class ElementAnimations;
 class Attr;
 class Attribute;
 class CSSStyleDeclaration;
 class ClientRect;
 class ClientRectList;
 class CustomElementDefinition;
 class DOMStringMap;
 class DOMTokenList;
 class Dictionary;
-class ElementIntersectionObserverData;
 class ElementRareData;
 class ElementShadow;
 class ExceptionState;
 class Image;
 class IntSize;
 class Locale;
 class MutableStylePropertySet;
+class NodeIntersectionObserverData;
 class PropertySetCSSStyleDeclaration;
 class PseudoElement;
 class ScrollState;
 class ScrollStateCallback;
 class ScrollToOptions;
 class ShadowRoot;
 class ShadowRootInit;
 class StylePropertySet;
 
 enum SpellcheckAttributeState {
@@ skipping 474 matching lines @@
     // the element is inDocument() and the context is an isolated world.
     void logAddElementIfIsolatedWorldAndInDocument(const char element[], const QualifiedName& attr1);
     void logAddElementIfIsolatedWorldAndInDocument(const char element[], const QualifiedName& attr1, const QualifiedName& attr2);
     void logAddElementIfIsolatedWorldAndInDocument(const char element[], const QualifiedName& attr1, const QualifiedName& attr2, const QualifiedName& attr3);
     void logUpdateAttributeIfIsolatedWorldAndInDocument(const char element[], const QualifiedName& attributeName, const AtomicString& oldValue, const AtomicString& newValue);
 
     DECLARE_VIRTUAL_TRACE();
 
     SpellcheckAttributeState spellcheckAttributeState() const;
 
-    ElementIntersectionObserverData* intersectionObserverData() const;
-    ElementIntersectionObserverData& ensureIntersectionObserverData();
+    NodeIntersectionObserverData* intersectionObserverData() const;
+    NodeIntersectionObserverData& ensureIntersectionObserverData();
 
 protected:
     Element(const QualifiedName& tagName, Document*, ConstructionType);
 
     const ElementData* elementData() const { return m_elementData.get(); }
     UniqueElementData& ensureUniqueElementData();
 
     void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*, CSSPropertyID, CSSValueID identifier);
     void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*, CSSPropertyID, double value, CSSPrimitiveValue::UnitType);
     void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*, CSSPropertyID, const String& value);
@@ skipping 370 matching lines @@
     static PassRefPtrWillBeRawPtr<T> create(const QualifiedName&, Document&)
 #define DEFINE_ELEMENT_FACTORY_WITH_TAGNAME(T) \
     PassRefPtrWillBeRawPtr<T> T::create(const QualifiedName& tagName, Document& document) \
     { \
         return adoptRefWillBeNoop(new T(tagName, document)); \
     }
 
 } // namespace
 
 #endif // Element_h