Remove attrs sky doesn't support.

sky/engine/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 Apple 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 191 matching lines @@
     if (!document.isActive())
         return;
 
     AtomicString imageSourceURL = m_element->imageSourceURL();
     KURL url = imageSourceToKURL(imageSourceURL);
     ResourcePtr<ImageResource> newImage = 0;
     if (!url.isNull()) {
         // Unlike raw <img>, we block mixed content inside of <picture> or <img srcset>.
         ResourceLoaderOptions resourceLoaderOptions = ResourceFetcher::defaultResourceOptions();
         ResourceRequest resourceRequest(url);
-        if (!element()->getAttribute(HTMLNames::srcsetAttr).isNull())
-            resourceRequest.setRequestContext(WebURLRequest::RequestContextImageSet);
         FetchRequest request(ResourceRequest(url), element()->localName(), resourceLoaderOptions);
 
         newImage = document.fetcher()->fetchImage(request);
 
         if (!newImage && !pageIsBeingDismissed(&document))
             crossSiteOrCSPViolationOccured(imageSourceURL);
         else
             clearFailedLoadURL();
     } else if (!imageSourceURL.isNull()) {
         // Fire an error event if the url string is not empty, but the KURL is.
@@ skipping 269 matching lines @@
 void ImageLoader::sourceImageChanged()
 {
     HashSet<ImageLoaderClient*>::iterator end = m_clients.end();
     for (HashSet<ImageLoaderClient*>::iterator it = m_clients.begin(); it != end; ++it) {
         ImageLoaderClient* handle = *it;
         handle->notifyImageSourceChanged();
     }
 }
 
 }