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

Source/core/svg/SVGTextContentElement.h

 /*
  * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2008 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 64 matching lines @@
     virtual bool selfHasRelativeLengths() const OVERRIDE;
 
 private:
     virtual bool isTextContent() const OVERRIDE FINAL { return true; }
 
     RefPtr<SVGAnimatedLength> m_textLength;
     bool m_textLengthIsSpecifiedByUser;
     RefPtr<SVGAnimatedEnumeration<SVGLengthAdjustType> > m_lengthAdjust;
 };
 
-inline bool isSVGTextContentElement(const Node& node)
+inline bool isSVGTextContentElement(const SVGElement& element)
 {
-    return node.isSVGElement() && toSVGElement(node).isTextContent();
+    return element.isTextContent();
 }
 
-DEFINE_ELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGTextContentElement);
+DEFINE_SVGELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGTextContentElement);
 
 } // namespace blink
 
 #endif