Clean up includes and forward-declarations in the flowthread / multicol files.

Source/core/rendering/RenderRegion.h

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. 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.
@@ skipping 13 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #ifndef RenderRegion_h
 #define RenderRegion_h
 
 #include "core/rendering/RenderBlockFlow.h"
-#include "core/rendering/style/StyleInheritedData.h"
 
 namespace blink {
 
-struct LayerFragment;
-typedef Vector<LayerFragment, 1> LayerFragments;
 class RenderFlowThread;
 
 class RenderRegion : public RenderBlockFlow {
 public:
     explicit RenderRegion(Element*, RenderFlowThread*);
 
     virtual bool isOfType(RenderObjectType type) const override { return type == RenderObjectRenderRegion || RenderBlockFlow::isOfType(type); }
 
     void setFlowThreadPortionRect(const LayoutRect& rect) { m_flowThreadPortionRect = rect; }
     LayoutRect flowThreadPortionRect() const { return m_flowThreadPortionRect; }
@@ skipping 35 matching lines @@
 private:
     LayoutRect m_flowThreadPortionRect;
     bool m_isValid : 1;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderRegion, isRenderRegion());
 
 } // namespace blink
 
 #endif // RenderRegion_h