Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

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 32 matching lines @@
 
     virtual void computePreferredLogicalWidths();
     virtual bool avoidsFloats() const { return true; }
 
     virtual bool supportsPartialLayout() const OVERRIDE { return false; }
 
     virtual void paintBoxDecorations(PaintInfo&, const LayoutPoint&);
     virtual void paintMask(PaintInfo&, const LayoutPoint&);
 };
 
-inline RenderFieldset* toRenderFieldset(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isFieldset());
-    return static_cast<RenderFieldset*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderFieldset(const RenderFieldset*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderFieldset, isFieldset());
 
 } // namespace WebCore
 
 #endif // RenderFieldset_h