Make RenderObject::style() return a const object

Source/core/svg/SVGSymbolElement.cpp

 /*
  * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
  *
  * 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,
@@ skipping 34 matching lines @@
 {
     parseAttributeNew(name, value);
 }
 
 void SVGSymbolElement::svgAttributeChanged(const QualifiedName& attrName)
 {
     if (SVGFitToViewBox::isKnownAttribute(attrName))
         invalidateInstances();
 }
 
-RenderObject* SVGSymbolElement::createRenderer(RenderStyle*)
+RenderObject* SVGSymbolElement::createRenderer(const RenderStyle*)
 {
     return new RenderSVGHiddenContainer(this);
 }
 
 }