Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderSlider.h

 /*
  * Copyright (C) 2006, 2007, 2008, 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 34 matching lines @@
 
     virtual int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const;
     virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const OVERRIDE;
     virtual void computePreferredLogicalWidths() OVERRIDE;
     virtual bool requiresForcedStyleRecalcPropagation() const { return true; }
     virtual void layout();
 
     SliderThumbElement* sliderThumbElement() const;
 };
 
-inline RenderSlider* toRenderSlider(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isSlider());
-    return static_cast<RenderSlider*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderSlider(const RenderSlider*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderSlider, isSlider());
 
 } // namespace WebCore
 
 #endif // RenderSlider_h