Enable srcset support in HTMLImageElement

Source/core/html/parser/HTMLSrcsetParser.h

Index: Source/core/html/parser/HTMLSrcsetParser.h
diff --git a/Source/core/html/parser/HTMLSrcsetParser.h b/Source/core/html/parser/HTMLSrcsetParser.h
new file mode 100644
index 0000000000000000000000000000000000000000..e4687afddaa7e22156a5391291c918deeb00133a
--- /dev/null
+++ b/Source/core/html/parser/HTMLSrcsetParser.h
@@ -0,0 +1,16 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef HTMLSrcsetParser_h
+#define HTMLSrcsetParser_h
+
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& srcAttribute, const String& sourceSetAttribute);
+
+}
+
+#endif