Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderTextControlSingleLine.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 66 matching lines @@
     virtual RenderStyle* textBaseStyle() const;
 
     bool textShouldBeTruncated() const;
 
     HTMLElement* innerSpinButtonElement() const;
 
     bool m_shouldDrawCapsLockIndicator;
     LayoutUnit m_desiredInnerTextLogicalHeight;
 };
 
-inline RenderTextControlSingleLine* toRenderTextControlSingleLine(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isTextField());
-    return static_cast<RenderTextControlSingleLine*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderTextControlSingleLine(const RenderTextControlSingleLine*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderTextControlSingleLine, isTextField());
 
 // ----------------------------
 
 class RenderTextControlInnerBlock : public RenderBlockFlow {
 public:
     RenderTextControlInnerBlock(Element* element) : RenderBlockFlow(element) { }
     virtual int inlineBlockBaseline(LineDirectionMode direction) const OVERRIDE { return lastLineBoxBaseline(direction); }
 
 private:
     virtual bool isIntristicallyScrollable(ScrollbarOrientation orientation) const OVERRIDE
     {
         return orientation == HorizontalScrollbar;
     }
     virtual bool scrollsOverflowX() const OVERRIDE { return hasOverflowClip(); }
     virtual bool scrollsOverflowY() const OVERRIDE { return false; }
     virtual bool hasLineIfEmpty() const OVERRIDE { return true; }
 };
 
 }
 
 #endif