Make manual isSVG*Element() helpers as efficient as the generated ones

Source/core/svg/SVGGraphicsElement.h

 /*
  * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2014 Google, Inc.
  *
  * 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 68 matching lines @@
 
     RefPtr<SVGAnimatedTransformList> m_transform;
 
 private:
     virtual bool isSVGGraphicsElement() const OVERRIDE FINAL { return true; }
 
     // Used by <animateMotion>
     OwnPtr<AffineTransform> m_supplementalTransform;
 };
 
-inline bool isSVGGraphicsElement(const Node& node)
+inline bool isSVGGraphicsElement(const SVGElement& element)
 {
-    return node.isSVGElement() && toSVGElement(node).isSVGGraphicsElement();
+    return element.isSVGGraphicsElement();
 }
 
-DEFINE_ELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGGraphicsElement);
+DEFINE_SVGELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGGraphicsElement);
 
 } // namespace blink
 
 #endif // SVGGraphicsElement_h