Forced style invalidation when clearing resolver no longer needed.

Source/core/dom/StyleEngine.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 476 matching lines @@
     // StyleEngine::shadowRootRemovedFromDocument removes not-in-document
     // treescopes from activeTreeScopes. StyleEngine::didRemoveShadowRoot
     // removes treescopes which are being destroyed from activeTreeScopes.
     // So we need to clearScopedStyleResolver for treescopes which have been
     // just removed from document. If document is destroyed before invoking
     // updateActiveStyleSheets, the treescope has a scopedStyleResolver which
     // has destroyed StyleSheetContents.
     for (UnorderedTreeScopeSet::iterator it = m_activeTreeScopes.beginUnordered(); it != m_activeTreeScopes.endUnordered(); ++it)
         (*it)->clearScopedStyleResolver();
 
-    if (m_resolver)
-        document().updateStyleInvalidationIfNeeded();
     m_resolver.clear();
 }
 
 void StyleEngine::clearMasterResolver()
 {
     if (Document* master = this->master())
         master->styleEngine().clearResolver();
 }
 
 unsigned StyleEngine::resolverAccessCount() const
@@ skipping 285 matching lines @@
     visitor->trace(m_dirtyTreeScopes);
     visitor->trace(m_activeTreeScopes);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
 #endif
     CSSFontSelectorClient::trace(visitor);
 }
 
 }