Smaller vtbls in RenderObject

Source/core/rendering/RenderIFrame.h

 /*
  * Copyright (C) 2010 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 22 matching lines @@
 class RenderIFrame final : public RenderPart {
 public:
     explicit RenderIFrame(Element*);
 
 private:
     virtual bool shouldComputeSizeAsReplaced() const override;
     virtual bool isInlineBlockOrInlineTable() const override;
 
     virtual void layout() override;
 
-    virtual bool isRenderIFrame() const override { return true; }
+    virtual bool isOfType(RenderObjectType type) const override { return type == RenderObjectRenderIFrame || RenderPart::isOfType(type); }
 
     virtual const char* renderName() const override { return "RenderPartObject"; } // Lying for now to avoid breaking tests
 
     virtual LayerType layerTypeRequired() const override;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderIFrame, isRenderIFrame());
 
 } // namespace blink
 
 #endif // RenderIFrame_h