Reduce forward declarations in core/rendering

Source/core/rendering/compositing/CompositingRequirementsUpdater.h

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google 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
@@ skipping 18 matching lines @@
 
 #include "platform/geometry/IntRect.h"
 #include "platform/graphics/CompositingReasons.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class CompositingReasonFinder;
 class RenderLayer;
 class RenderObject;
-class RenderPart;
 class RenderView;
 
 class CompositingRequirementsUpdater {
 public:
     CompositingRequirementsUpdater(RenderView&, CompositingReasonFinder&);
     ~CompositingRequirementsUpdater();
 
     //  Recurse through the layers in z-index and overflow order (which is equivalent to painting order)
     //  For the z-order children of a compositing layer:
     //      If a child layers has a compositing layer, then all subsequent layers must
@@ skipping 12 matching lines @@
     void updateRecursive(RenderLayer* ancestorLayer, RenderLayer* currentLayer, OverlapMap&, RecursionData&, bool& descendantHas3DTransform, Vector<RenderLayer*>& unclippedDescendants, IntRect& absoluteDecendantBoundingBox);
     bool isRunningAcceleratedTransformAnimation(RenderObject*) const;
 
     RenderView& m_renderView;
     CompositingReasonFinder& m_compositingReasonFinder;
 };
 
 } // namespace WebCore
 
 #endif // CompositingRequirementsUpdater_h