Implement compositing bounds in CompositingDisplayItem

Source/core/paint/CompositingRecorder.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CompositingRecorder_h
 #define CompositingRecorder_h
 
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/GraphicsTypes.h"
 #include "platform/graphics/paint/DisplayItem.h"
 #include "public/platform/WebBlendMode.h"
 
 namespace blink {
 
 class GraphicsContext;
 class LayoutObject;
 
 class CompositingRecorder {
 public:
-    explicit CompositingRecorder(GraphicsContext*, DisplayItemClient, const SkXfermode::Mode, const float, const FloatRect* = 0, ColorFilter = ColorFilterNone);
+    explicit CompositingRecorder(GraphicsContext*, DisplayItemClient, const SkXfermode::Mode, const float, const FloatRect* bounds = 0, ColorFilter = ColorFilterNone);
 
     ~CompositingRecorder();
 
 private:
     DisplayItemClient m_client;
     GraphicsContext* m_graphicsContext;
 };
 
 } // namespace blink
 
 #endif // CompositingRecorder_h