Clean up forward declarations in Source/core/frame

Source/core/frame/Navigator.h

 /*
     Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
 
     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
@@ skipping 20 matching lines @@
 #include "wtf/Forward.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class DOMMimeTypeArray;
 class DOMPluginArray;
 class LocalFrame;
-class PluginData;
 
 typedef int ExceptionCode;
 
 class Navigator FINAL
     : public RefCountedWillBeGarbageCollectedFinalized<Navigator>
     , public NavigatorCPU
     , public NavigatorID
     , public NavigatorLanguage
     , public NavigatorOnLine
     , public ScriptWrappable
@@ skipping 31 matching lines @@
 private:
     explicit Navigator(LocalFrame*);
 
     mutable RefPtrWillBeMember<DOMPluginArray> m_plugins;
     mutable RefPtrWillBeMember<DOMMimeTypeArray> m_mimeTypes;
 };
 
 } // namespace blink
 
 #endif // Navigator_h