Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderHTMLCanvas.h

 /*
  * Copyright (C) 2004, 2006, 2007, 2009 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 29 matching lines @@
     virtual bool requiresLayer() const;
 
     void canvasSizeChanged();
 
 private:
     virtual const char* renderName() const { return "RenderHTMLCanvas"; }
     virtual void paintReplaced(PaintInfo&, const LayoutPoint&);
     virtual void intrinsicSizeChanged() { canvasSizeChanged(); }
 };
 
-inline RenderHTMLCanvas* toRenderHTMLCanvas(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isCanvas());
-    return static_cast<RenderHTMLCanvas*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderHTMLCanvas(const RenderHTMLCanvas*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderHTMLCanvas, isCanvas());
 
 } // namespace WebCore
 
 #endif // RenderHTMLCanvas_h