Enable srcset support in HTMLImageElement

Source/core/html/HTMLImageElement.cpp

Index: Source/core/html/HTMLImageElement.cpp
diff --git a/Source/core/html/HTMLImageElement.cpp b/Source/core/html/HTMLImageElement.cpp
index bf88109ed9ecad7b640245f02d5216edaa77a176..94de19bed414eb8f3f9947ad9d5d9500adf81996 100644
--- a/Source/core/html/HTMLImageElement.cpp
+++ b/Source/core/html/HTMLImageElement.cpp
@@ -107,13 +107,20 @@ void HTMLImageElement::collectStyleForPresentationAttribute(const QualifiedName&
         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)