Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderBR.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 42 matching lines @@
 
     virtual PositionWithAffinity positionForPoint(const LayoutPoint&) OVERRIDE FINAL;
 
 protected:
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle);
 
 private:
     mutable int m_lineHeight;
 };
 
-
-inline RenderBR* toRenderBR(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isBR());
-    return static_cast<RenderBR*>(object);
-}
-
-inline const RenderBR* toRenderBR(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isBR());
-    return static_cast<const RenderBR*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderBR(const RenderBR*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBR, isBR());
 
 } // namespace WebCore
 
 #endif // RenderBR_h