Should check whether document.settings() is available or not when updating GenericFontFamilySetting…

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 507 matching lines @@
 {
     // We should not recreate FontSelector. Instead, clear fontFaceCache.
     if (m_fontSelector)
         m_fontSelector->fontFaceCache()->clear();
     if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
 }
 
 void StyleEngine::updateGenericFontFamilySettings()
 {
+    // FIXME: we should not update generic font family settings when
+    // document is inactive.
+    ASSERT(document().isActive());
+
     if (!m_fontSelector)
         return;
 
     m_fontSelector->updateGenericFontFamilySettings(*m_document);
     if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
 }
 
 void StyleEngine::removeFontFaceRules(const WillBeHeapVector<RawPtrWillBeMember<const StyleRuleFontFace> >& fontFaceRules)
 {
@@ skipping 108 matching lines @@
     visitor->trace(m_documentStyleSheetCollection);
     visitor->trace(m_styleSheetCollectionMap);
     visitor->trace(m_resolver);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
     CSSFontSelectorClient::trace(visitor);
 }
 
 }