Implement ParentNode IDL interface

Source/core/html/HTMLElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 23 matching lines @@
 enum TranslateAttributeMode {
     TranslateAttributeYes,
     TranslateAttributeNo,
     TranslateAttributeInherit
 };
 
 class HTMLElement : public StyledElement {
 public:
     static PassRefPtr<HTMLElement> create(const QualifiedName& tagName, Document*);
 
-    PassRefPtr<HTMLCollection> children();
-
     virtual String title() const OVERRIDE FINAL;
 
     virtual short tabIndex() const;
     void setTabIndex(int);
 
     String innerHTML() const;
     String outerHTML() const;
     void setInnerHTML(const String&, ExceptionCode&);
     void setOuterHTML(const String&, ExceptionCode&);
     void setInnerText(const String&, ExceptionCode&);
@@ skipping 93 matching lines @@
 inline HTMLElement::HTMLElement(const QualifiedName& tagName, Document* document, ConstructionType type = CreateHTMLElement)
     : StyledElement(tagName, document, type)
 {
     ASSERT(tagName.localName().impl());
     ScriptWrappable::init(this);
 }
 
 } // namespace WebCore
 
 #endif // HTMLElement_h