Enable srcset support in HTMLImageElement

Source/core/html/HTMLImageElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * 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 89 matching lines @@
         addHTMLLengthToStyle(style, CSSPropertyMarginLeft, value);
         addHTMLLengthToStyle(style, CSSPropertyMarginRight, value);
     } else if (name == alignAttr)
         applyAlignmentAttributeToStyle(value, style);
     else if (name == valignAttr)
         addPropertyToPresentationAttributeStyle(style, CSSPropertyVerticalAlign, value);
     else
         HTMLElement::collectStyleForPresentationAttribute(name, value, style);
 }
 
+const AtomicString HTMLImageElement::imageSourceURL() const
+{
+    return m_bestFitImageURL.isEmpty() ? fastGetAttribute(srcAttr) : m_bestFitImageURL;
+}
+
 void HTMLImageElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == altAttr) {
         if (renderer() && renderer()->isImage())
             toRenderImage(renderer())->updateAltText();
-    } else if (name == srcAttr)
+    } else if (name == srcAttr || name == srcsetAttr) {
+        m_bestFitImageURL = bestFitSourceForImageAttributes(document().devicePixelRatio(), fastGetAttribute(srcAttr), fastGetAttribute(srcsetAttr));
         m_imageLoader.updateFromElementIgnoringPreviousError();
+    }
     else if (name == usemapAttr)
         setIsLink(!value.isNull());
     else if (name == onbeforeloadAttr)
         setAttributeEventListener(eventNames().beforeloadEvent, createAttributeEventListener(this, name, value));
     else if (name == compositeAttr) {
         // FIXME: images don't support blend modes in their compositing attribute.
         BlendMode blendOp = BlendModeNormal;
         if (!parseCompositeAndBlendOperator(value, m_compositeOperator, blendOp))
             m_compositeOperator = CompositeSourceOver;
     } else
@@ skipping 240 matching lines @@
 
 Image* HTMLImageElement::imageContents()
 {
     if (!m_imageLoader.imageComplete())
         return 0;
 
     return m_imageLoader.image()->image();
 }
 
 }