Reduce forward declarations in core/rendering

Source/core/rendering/LayoutState.h

 /*
  * Copyright (C) 2007 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 #define LayoutState_h
 
 #include "core/rendering/ColumnInfo.h"
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/HashMap.h"
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
 class ForceHorriblySlowRectMapping;
-class RenderBlockFlow;
 class RenderBox;
 class RenderObject;
-class RenderFlowThread;
 class RenderView;
 
 class LayoutState {
     WTF_MAKE_NONCOPYABLE(LayoutState);
 public:
     // Constructor for root LayoutState created by RenderView
     LayoutState(LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged, RenderView&);
     // Constructor for sub-tree Layout and RenderTableSections
     explicit LayoutState(RenderObject& root);
 
@@ skipping 91 matching lines @@
     LayoutUnit m_pageLogicalHeight;
     // The offset of the start of the first page in the nearest enclosing pagination model.
     LayoutSize m_pageOffset;
 
     RenderObject& m_renderer;
 };
 
 } // namespace WebCore
 
 #endif // LayoutState_h