Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderListItem.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 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 74 matching lines @@
 
     int m_explicitValue;
     RenderListMarker* m_marker;
     mutable int m_value;
 
     bool m_hasExplicitValue : 1;
     mutable bool m_isValueUpToDate : 1;
     bool m_notInList : 1;
 };
 
-inline RenderListItem* toRenderListItem(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isListItem());
-    return static_cast<RenderListItem*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderListItem(const RenderListItem*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderListItem, isListItem());
 
 } // namespace WebCore
 
 #endif // RenderListItem_h