Defer style recalc when inserting extension stylesheets.

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 213 matching lines @@
     m_injectedStyleSheetCacheValid = false;
     markDocumentDirty();
     // FIXME: updateInjectedStyleSheetCache is called inside StyleSheetCollection::updateActiveStyleSheets
     // and batch updates lots of sheets so we can't call addedStyleSheet() or removedStyleSheet().
     document().styleResolverChanged(RecalcStyleDeferred);
 }
 
 void StyleEngine::addAuthorSheet(PassRefPtrWillBeRawPtr<StyleSheetContents> authorSheet)
 {
     m_authorStyleSheets.append(CSSStyleSheet::create(authorSheet, m_document));
-    document().addedStyleSheet(m_authorStyleSheets.last().get(), RecalcStyleImmediately);
+    document().addedStyleSheet(m_authorStyleSheets.last().get(), RecalcStyleDeferred);
     markDocumentDirty();
 }
 
 void StyleEngine::addPendingSheet()
 {
     m_pendingStylesheets++;
 }
 
 // This method is called whenever a top-level stylesheet has finished loading.
 void StyleEngine::removePendingSheet(Node* styleSheetCandidateNode, RemovePendingSheetNotificationType notification)
@@ skipping 391 matching lines @@
     visitor->trace(m_authorStyleSheets);
     visitor->trace(m_documentStyleSheetCollection);
     visitor->trace(m_styleSheetCollectionMap);
     visitor->trace(m_resolver);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
 }
 
 }