Add toSVGStopElement(Node* node) to clean-up a static_cast<SVGStopElement*>

Source/core/svg/SVGStopElement.h

 /*
  * Copyright (C) 2004, 2005, 2007, 2008 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef SVGStopElement_h
 #define SVGStopElement_h
 
+#include "SVGNames.h"
 #include "core/svg/SVGAnimatedNumber.h"
 #include "core/svg/SVGElement.h"
 
 namespace WebCore {
 
 class SVGStopElement FINAL : public SVGElement {
 public:
     static PassRefPtr<SVGStopElement> create(const QualifiedName&, Document*);
 
     Color stopColorIncludingOpacity() const;
 
 private:
     SVGStopElement(const QualifiedName&, Document*);
 
     bool isSupportedAttribute(const QualifiedName&);
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual void svgAttributeChanged(const QualifiedName&);
 
     virtual bool isGradientStop() const OVERRIDE { return true; }
 
     virtual RenderObject* createRenderer(RenderStyle*);
     virtual bool rendererIsNeeded(const NodeRenderingContext&) OVERRIDE;
 
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGStopElement)
         DECLARE_ANIMATED_NUMBER(Offset, offset)
     END_DECLARE_ANIMATED_PROPERTIES
 };
 
+inline SVGStopElement* toSVGStopElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || node->hasTagName(SVGNames::stopTag));
+    return static_cast<SVGStopElement*>(node);
+}
+
 inline SVGStopElement* toSVGStopElement(SVGElement* element)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!element || element->isGradientStop());
     return static_cast<SVGStopElement*>(element);
 }
 
 } // namespace WebCore
 
 #endif