Set root clip layer not to maskToBounds.

Source/web/PinchViewports.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 41 matching lines @@
 class WebViewImpl;
 
 class PinchViewports : WebCore::GraphicsLayerClient {
 public:
     static PassOwnPtr<PinchViewports> create(WebViewImpl* owner);
     ~PinchViewports();
 
     void setOverflowControlsHostLayer(WebCore::GraphicsLayer*);
     WebCore::GraphicsLayer* rootGraphicsLayer()
     {
-        return m_innerViewportClipLayer.get();
+        return m_innerViewportContainerLayer.get();
     }
     void setViewportSize(const WebCore::IntSize&);
 
     void registerViewportLayersWithTreeView(WebLayerTreeView*) const;
     void clearViewportLayersForTreeView(WebLayerTreeView*) const;
 
     // GraphicsLayerClient implementation.
     virtual void notifyAnimationStarted(const WebCore::GraphicsLayer*, double time) OVERRIDE;
     virtual void paintContents(const WebCore::GraphicsLayer*, WebCore::GraphicsContext&, WebCore::GraphicsLayerPaintingPhase, const WebCore::IntRect& inClip) OVERRIDE;
 
 private:
     explicit PinchViewports(WebViewImpl* owner);
 
     void setupScrollbar(WebKit::WebScrollbar::Orientation);
 
     WebViewImpl* m_owner;
-    OwnPtr<WebCore::GraphicsLayer> m_innerViewportClipLayer;
+    OwnPtr<WebCore::GraphicsLayer> m_innerViewportContainerLayer;
     OwnPtr<WebCore::GraphicsLayer> m_pageScaleLayer;
     OwnPtr<WebCore::GraphicsLayer> m_innerViewportScrollLayer;
     OwnPtr<WebCore::GraphicsLayer> m_overlayScrollbarHorizontal;
     OwnPtr<WebCore::GraphicsLayer> m_overlayScrollbarVertical;
 };
 
 } // namespace WebKit
 
 #endif // PinchViewports_h