Reduce forward declarations in core/dom

Source/core/dom/DocumentMarkerController.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 17 matching lines @@
 #define DocumentMarkerController_h
 
 #include "core/dom/DocumentMarker.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashMap.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
-class ContainerNode;
 class LayoutPoint;
 class LayoutRect;
 class Node;
 class Range;
 class RenderedDocumentMarker;
 
 class DocumentMarkerController FINAL : public NoBaseWillBeGarbageCollected<DocumentMarkerController> {
     WTF_MAKE_NONCOPYABLE(DocumentMarkerController); WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
     DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(DocumentMarkerController);
 public:
@@ skipping 52 matching lines @@
     DocumentMarker::MarkerTypes m_possiblyExistingMarkerTypes;
 };
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 void showDocumentMarkers(const WebCore::DocumentMarkerController*);
 #endif
 
 #endif // DocumentMarkerController_h