Add SVGFitToViewBox::hasValidViewBox helper

third_party/WebKit/Source/core/svg/SVGViewSpec.h

 /*
  * Copyright (C) 2007 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
@@ skipping 47 matching lines @@
   void setViewBox(const FloatRect&);
   void setPreserveAspectRatio(const SVGPreserveAspectRatio&);
 
   Member<SVGRect> m_viewBox;
   Member<SVGPreserveAspectRatio> m_preserveAspectRatio;
   Member<SVGTransformList> m_transform;
 };
 
 template <typename T>
 void SVGViewSpec::inheritViewAttributesFromElement(T& inheritFromElement) {
-  if (inheritFromElement.viewBox()->currentValue()->isValid())
+  if (inheritFromElement.hasValidViewBox())
     setViewBox(inheritFromElement.viewBox()->currentValue()->value());
 
   if (inheritFromElement.preserveAspectRatio()->isSpecified()) {
     setPreserveAspectRatio(
         *inheritFromElement.preserveAspectRatio()->currentValue());
   }
 
   if (inheritFromElement.hasAttribute(SVGNames::zoomAndPanAttr))
     setZoomAndPan(inheritFromElement.zoomAndPan());
 }
 
 }  // namespace blink
 
 #endif  // SVGViewSpec_h