Get rid of the remaining uses of GraphicsLayer.

sky/engine/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2069 matching lines @@
 
     if (shouldIncludeTransform)
         result = transform()->mapRect(result);
 
     LayoutPoint delta;
     convertToLayerCoords(ancestorLayer, delta);
     result.moveBy(delta);
     return result;
 }
 
-GraphicsLayer* RenderLayer::graphicsLayerBacking() const
-{
-    return 0;
-}
-
 bool RenderLayer::hasCompositedMask() const
 {
     // FIXME(sky): Remove
     return false;
 }
 
 bool RenderLayer::hasCompositedClippingMask() const
 {
     // FIXME(sky): Remove
     return false;
@@ skipping 243 matching lines @@
     }
 }
 
 void showLayerTree(const blink::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif