Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderMenuList.h

 /*
  * This file is part of the select element renderer in WebCore.
  *
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 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 123 matching lines @@
     int m_optionsWidth;
 
     int m_lastActiveIndex;
 
     RefPtr<RenderStyle> m_optionStyle;
 
     RefPtr<PopupMenu> m_popup;
     bool m_popupIsVisible;
 };
 
-inline RenderMenuList* toRenderMenuList(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isMenuList());
-    return static_cast<RenderMenuList*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderMenuList(const RenderMenuList*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderMenuList, isMenuList());
 
 }
 
 #endif