Collect active stylesheets and and apply asynchronously.

third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc.
  * All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
@@ skipping 1617 matching lines @@
     const MatchedProperties* properties,
     unsigned size) {
   return StringHasher::hashMemory(properties, sizeof(MatchedProperties) * size);
 }
 
 void StyleResolver::invalidateMatchedPropertiesCache() {
   m_matchedPropertiesCache.clear();
 }
 
 void StyleResolver::notifyResizeForViewportUnits() {
+  document().styleEngine().updateActiveStyle();
   m_matchedPropertiesCache.clearViewportDependent();
 }
 
 void StyleResolver::applyMatchedPropertiesAndCustomPropertyAnimations(
     StyleResolverState& state,
     const MatchResult& matchResult,
     const Element* animatingElement) {
   CacheSuccess cacheSuccess = applyMatchedCache(state, matchResult);
   NeedsApplyPass needsApplyPass;
   if (!cacheSuccess.isFullCacheHit()) {
@@ skipping 334 matching lines @@
 DEFINE_TRACE(StyleResolver) {
   visitor->trace(m_matchedPropertiesCache);
   visitor->trace(m_selectorFilter);
   visitor->trace(m_styleSharingLists);
   visitor->trace(m_pendingStyleSheets);
   visitor->trace(m_document);
   visitor->trace(m_tracker);
 }
 
 }  // namespace blink