Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderSearchField.h

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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 26 matching lines @@
 
 private:
     virtual void centerContainerIfNeeded(RenderBox*) const OVERRIDE;
     virtual LayoutUnit computeControlLogicalHeight(LayoutUnit lineHeight, LayoutUnit nonContentHeight) const OVERRIDE;
     virtual LayoutUnit computeLogicalHeightLimit() const OVERRIDE;
 
     Element* searchDecorationElement() const;
     Element* cancelButtonElement() const;
 };
 
-inline RenderSearchField* toRenderSearchField(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isTextField());
-    return static_cast<RenderSearchField*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderSearchField(const RenderSearchField*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderSearchField, isTextField());
 
 }
 
 #endif