Turn styleWillChange |newStyle| into a reference

Source/core/rendering/RenderButton.h

 /*
  * Copyright (C) 2005 Apple Computer
  *
  * 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 41 matching lines @@
     // <button> should allow whitespace even though RenderFlexibleBox doesn't.
     virtual bool canHaveWhitespaceChildren() const OVERRIDE { return true; }
 
     virtual bool canHaveGeneratedChildren() const OVERRIDE;
     virtual bool hasControlClip() const OVERRIDE { return true; }
     virtual LayoutRect controlClipRect(const LayoutPoint&) const OVERRIDE;
 
     virtual int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode) const OVERRIDE;
 
 private:
-    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle) OVERRIDE;
+    virtual void styleWillChange(StyleDifference, const RenderStyle& newStyle) OVERRIDE;
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) OVERRIDE;
 
     virtual bool hasLineIfEmpty() const OVERRIDE { return isHTMLInputElement(node()); }
 
     RenderBlock* m_inner;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderButton, isRenderButton());
 
 } // namespace WebCore
 
 #endif // RenderButton_h