Add SVGFitToViewBox::hasValidViewBox helper

third_party/WebKit/Source/core/svg/SVGSVGElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * 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 564 matching lines @@
     synthesizedViewBoxSize.setHeight(
         height()->currentValue()->scaleByPercentage(
             currentViewportSize().height()));
   return FloatRect(FloatPoint(), synthesizedViewBoxSize);
 }
 
 SVGPreserveAspectRatio* SVGSVGElement::currentPreserveAspectRatio() const {
   if (m_viewSpec)
     return m_viewSpec->preserveAspectRatio();
 
-  if (!viewBox()->currentValue()->isValid() && shouldSynthesizeViewBox()) {
-    // If no viewBox is specified and we're embedded through SVGImage, then
-    // synthesize a pAR with the value 'none'.
+  if (!hasValidViewBox() && shouldSynthesizeViewBox()) {
+    // If no (valid) viewBox is specified and we're embedded through SVGImage,
+    // then synthesize a pAR with the value 'none'.
     SVGPreserveAspectRatio* synthesizedPAR = SVGPreserveAspectRatio::create();
     synthesizedPAR->setAlign(
         SVGPreserveAspectRatio::kSvgPreserveaspectratioNone);
     return synthesizedPAR;
   }
   return preserveAspectRatio()->currentValue();
 }
 
 FloatSize SVGSVGElement::currentViewportSize() const {
   if (!layoutObject())
@@ skipping 129 matching lines @@
   visitor->trace(m_width);
   visitor->trace(m_height);
   visitor->trace(m_translation);
   visitor->trace(m_timeContainer);
   visitor->trace(m_viewSpec);
   SVGGraphicsElement::trace(visitor);
   SVGFitToViewBox::trace(visitor);
 }
 
 }  // namespace blink