Have srcset respond to viewport changes

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 3388 matching lines @@
 }
 
 void Document::evaluateMediaQueryList()
 {
     if (m_mediaQueryMatcher)
         m_mediaQueryMatcher->mediaFeaturesChanged();
 }
 
 void Document::notifyResizeForViewportUnits()
 {
+    if (m_mediaQueryMatcher)
+        m_mediaQueryMatcher->viewportChanged();
     if (!hasViewportUnits())
         return;
     ensureStyleResolver().notifyResizeForViewportUnits();
     setNeedsStyleRecalcForViewportUnits();
 }
 
 void Document::styleResolverChanged(StyleResolverUpdateMode updateMode)
 {
     // styleResolverChanged() can be invoked during Document destruction.
     // We just skip that case.
@@ skipping 2475 matching lines @@
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (WeakDocumentSet::const_iterator it = set.begin(); it != set.end(); ++it) {
         fprintf(stderr, "- Document %p URL: %s\n", *it, (*it)->url().string().utf8().data());
     }
 }
 #endif