Convert CompositingLayerMapping code to use reference

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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>
@@ skipping 81 matching lines @@
 // FIXME: remove this once the compositing query ASSERTS are no longer hit.
 class DisableCompositingQueryAsserts {
     WTF_MAKE_NONCOPYABLE(DisableCompositingQueryAsserts);
 public:
     DisableCompositingQueryAsserts();
 private:
     TemporaryChange<CompositingQueryMode> m_disabler;
 };
 
 class RenderLayer {
+    WTF_MAKE_NONCOPYABLE(RenderLayer);
 public:
     friend class RenderReplica;
     // FIXME: Needed until we move all the necessary bits to the new class.
     friend class RenderLayerStackingNode;
     // FIXME: Needed until we move all the necessary bits to the new class.
     friend class RenderLayerScrollableArea;
 
     RenderLayer(RenderLayerModelObject*, LayerType);
     ~RenderLayer();
 
@@ skipping 654 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h