Prefer to forward-declare GraphicsContext in headers.

Source/core/rendering/compositing/CompositingRequirementsUpdater.cpp

 /*
  * 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 13 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/rendering/compositing/CompositingRequirementsUpdater.h"
 
 #include "core/rendering/RenderLayerStackingNode.h"
 #include "core/rendering/RenderLayerStackingNodeIterator.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/compositing/RenderLayerCompositor.h"
+#include "platform/TraceEvent.h"
 
 namespace WebCore {
 
 class OverlapMapContainer {
 public:
     void add(const IntRect& bounds)
     {
         m_layerRects.append(bounds);
         m_boundingBox.unite(bounds);
     }
@@ skipping 412 matching lines @@
     layer->setCompositingReasons(reasonsToComposite);
 
 }
 
 bool CompositingRequirementsUpdater::isRunningAcceleratedTransformAnimation(RenderObject* renderer) const
 {
     return renderer->style()->hasCurrentTransformAnimation();
 }
 
 } // namespace WebCore