Smaller vtbls in RenderObject

Source/core/rendering/RenderFieldset.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 19 matching lines @@
 
 class RenderFieldset final : public RenderBlockFlow {
 public:
     explicit RenderFieldset(Element*);
 
     enum FindLegendOption { IgnoreFloatingOrOutOfFlow, IncludeFloatingOrOutOfFlow };
     RenderBox* findLegend(FindLegendOption = IgnoreFloatingOrOutOfFlow) const;
 
 private:
     virtual const char* renderName() const override { return "RenderFieldSet"; }
-    virtual bool isFieldset() const override { return true; }
+    virtual bool isOfType(RenderObjectType type) const override { return type == RenderObjectFieldset || RenderBlockFlow::isOfType(type); }
 
     virtual RenderObject* layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope&) override;
 
     virtual void computePreferredLogicalWidths() override;
     virtual bool avoidsFloats() const override { return true; }
 
     virtual void paintBoxDecorationBackground(PaintInfo&, const LayoutPoint&) override;
     virtual void paintMask(PaintInfo&, const LayoutPoint&) override;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderFieldset, isFieldset());
 
 } // namespace blink
 
 #endif // RenderFieldset_h