Clean up forward declarations in Source/core/page

Source/core/page/Page.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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,
@@ skipping 36 matching lines @@
 class ContextMenuClient;
 class ContextMenuController;
 class Document;
 class DragCaretController;
 class DragClient;
 class DragController;
 class EditorClient;
 class FocusController;
 class Frame;
 class FrameHost;
-class HistoryItem;
 class InspectorClient;
 class InspectorController;
 class PageLifecycleNotifier;
-class PlatformMouseEvent;
 class PluginData;
 class PointerLockController;
-class Range;
-class RenderBox;
-class RenderObject;
-class RenderTheme;
 class StorageClient;
-class VisibleSelection;
-class ScrollableArea;
 class ScrollingCoordinator;
 class Settings;
 class SpellCheckerClient;
 class StorageNamespace;
 class UndoStack;
 class ValidationMessageClient;
 
 typedef uint64_t LinkHash;
 
 float deviceScaleFactor(LocalFrame*);
@@ skipping 227 matching lines @@
     WillBeHeapHashSet<RawPtrWillBeWeakMember<MultisamplingChangedObserver> > m_multisamplingChangedObservers;
 
     // A pointer to all the interfaces provided to in-process Frames for this Page.
     // FIXME: Most of the members of Page should move onto FrameHost.
     OwnPtrWillBeMember<FrameHost> m_frameHost;
 };
 
 } // namespace blink
 
 #endif // Page_h