Set proper referrer for css resource fetching

Source/core/css/CSSImageValue.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2008 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 44 matching lines @@
 }
 
 StyleFetchedImage* CSSImageValue::cachedImage(ResourceFetcher* fetcher, const ResourceLoaderOptions& options)
 {
     ASSERT(fetcher);
 
     if (!m_accessedImage) {
         m_accessedImage = true;
 
         FetchRequest request(ResourceRequest(m_absoluteURL), m_initiatorName.isEmpty() ? FetchInitiatorTypeNames::css : m_initiatorName, options);
+        if (!m_referrer.isEmpty())
+            request.mutableResourceRequest().setHTTPReferrer(Referrer(m_referrer, ReferrerPolicyDefault));
 
         if (options.corsEnabled == IsCORSEnabled)
             request.setCrossOriginAccessControl(fetcher->document()->securityOrigin(), options.allowCredentials, options.credentialsRequested);
 
         if (ResourcePtr<ImageResource> cachedImage = fetcher->fetchImage(request))
             m_image = StyleFetchedImage::create(cachedImage.get());
     }
 
     return (m_image && m_image->isImageResource()) ? toStyleFetchedImage(m_image) : 0;
 }
@@ skipping 39 matching lines @@
 {
     KURL url = document.completeURL(m_relativeURL);
     if (url == m_absoluteURL)
         return;
     m_absoluteURL = url.string();
     m_accessedImage = false;
     m_image.clear();
 }
 
 } // namespace WebCore