Don't walk treescopes in updateActiveStyleSheets until the resolver exists.

sky/engine/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 53 matching lines @@
 }
 
 void StyleEngine::removeTreeScope(TreeScope& scope)
 {
     m_activeTreeScopes.remove(&scope);
 }
 
 void StyleEngine::updateActiveStyleSheets()
 {
     ASSERT(!m_document->inStyleRecalc());
-
-    if (!m_document->isActive())
-        return;
+    ASSERT(m_resolver);
 
     for (TreeScope* treeScope : m_activeTreeScopes)
-        treeScope->styleSheets().updateActiveStyleSheets(this);
+        treeScope->styleSheets().updateActiveStyleSheets(*m_resolver);
 }
 
 void StyleEngine::appendActiveAuthorStyleSheets()
 {
     for (TreeScope* treeScope : m_activeTreeScopes)
         m_resolver->appendAuthorStyleSheets(treeScope->styleSheets().activeAuthorStyleSheets());
 
     m_resolver->finishAppendAuthorStyleSheets();
 }
 
@@ skipping 16 matching lines @@
     m_resolver.clear();
 }
 
 unsigned StyleEngine::resolverAccessCount() const
 {
     return m_resolver ? m_resolver->accessCount() : 0;
 }
 
 void StyleEngine::resolverChanged()
 {
-    // Don't bother updating, since we haven't loaded all our style info yet
-    // and haven't calculated the style selector for the first time.
-    if (!m_document->isActive()) {
-        clearResolver();
+    if (!m_document->isActive())
         return;
-    }
-
-    updateActiveStyleSheets();
+    if (m_resolver)
+        updateActiveStyleSheets();
 }
 
 void StyleEngine::clearFontCache()
 {
     m_fontSelector->fontFaceCache()->clearCSSConnected();
     if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
 }
 
 void StyleEngine::updateGenericFontFamilySettings()
@@ skipping 41 matching lines @@
 }
 
 void StyleEngine::fontsNeedUpdate(CSSFontSelector*)
 {
     if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
     m_document->setNeedsStyleRecalc(SubtreeStyleChange);
 }
 
 }