StyleResolver should update RuleSets lazily.

Source/core/css/StyleMedia.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 43 matching lines @@
     if (!m_frame)
         return false;
 
     Document* document = m_frame->document();
     ASSERT(document);
     Element* documentElement = document->documentElement();
     if (!documentElement)
         return false;
 
     StyleResolver* styleResolver = document->styleResolver();
-    if (!styleResolver)
-        return false;
+    ASSERT(styleResolver);
+    appendPendingStyleSheetsIfNeeded(styleResolver);
 
     RefPtr<RenderStyle> rootStyle = styleResolver->styleForElement(documentElement, 0 /*defaultParent*/, DisallowStyleSharing, MatchOnlyUserAgentRules);
 
     RefPtr<MediaQuerySet> media = MediaQuerySet::create();
     if (!media->set(query))
         return false;
 
     MediaQueryEvaluator screenEval(type(), m_frame, rootStyle.get());
     return screenEval.eval(media.get());
 }
 
 } // namespace WebCore