Clean up forward declarations in Source/core/html

Source/core/html/parser/HTMLElementStack.h

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 19 matching lines @@
 #include "core/html/parser/HTMLStackItem.h"
 #include "wtf/Forward.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class ContainerNode;
-class DocumentFragment;
 class Element;
 class QualifiedName;
 
 // NOTE: The HTML5 spec uses a backwards (grows downward) stack.  We're using
 // more standard (grows upwards) stack terminology here.
 class HTMLElementStack {
     WTF_MAKE_NONCOPYABLE(HTMLElementStack);
     DISALLOW_ALLOCATION();
 public:
     HTMLElementStack();
@@ skipping 134 matching lines @@
     // way down through createElement, etc.
     RawPtrWillBeMember<ContainerNode> m_rootNode;
     RawPtrWillBeMember<Element> m_headElement;
     RawPtrWillBeMember<Element> m_bodyElement;
     unsigned m_stackDepth;
 };
 
 } // namespace blink
 
 #endif // HTMLElementStack_h