StyleResolver should update RuleSets lazily.

Source/core/dom/Document.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 1733 matching lines @@
         clearChildNeedsStyleRecalc();
         unscheduleStyleRecalc();
 
         // FIXME: SVG <use> element can schedule a recalc in the middle of an already running one.
         // See StyleEngine::updateActiveStyleSheets.
         if (m_styleEngine->needsUpdateActiveStylesheetsOnStyleRecalc())
             setNeedsStyleRecalc();
 
         if (m_styleResolver) {
             // Pseudo element removal and similar may only work with these flags still set. Reset them after the style recalc.
-            m_styleEngine->resetCSSFeatureFlags(m_styleResolver->ruleFeatureSet());
+            m_styleEngine->resetCSSFeatureFlags(m_styleResolver->ensureRuleFeatureSet());
             m_styleResolver->clearStyleSharingList();
         }
     }
 
     InspectorInstrumentation::didRecalculateStyle(cookie);
 
     // As a result of the style recalculation, the currently hovered element might have been
     // detached (for example, by setting display:none in the :hover style), schedule another mouseMove event
     // to check if any other elements ended up under the mouse pointer due to re-layout.
     if (hoverNode() && !hoverNode()->renderer() && frame())
@@ skipping 188 matching lines @@
 void Document::setIsViewSource(bool isViewSource)
 {
     m_isViewSource = isViewSource;
     if (!m_isViewSource)
         return;
 
     setSecurityOrigin(SecurityOrigin::createUnique());
     didUpdateSecurityOrigin();
 }
 
+StyleResolver* Document::styleResolver()

[esprehn, 2013/11/15 10:36:32]

We might need to make this inline later, but this is fine for this patch. Lets
micro optimize in the future.

[tasak, 2013/11/18 08:30:53]

I made this inline.

+{
+    if (!m_styleResolver) {
+        createStyleResolver();
+    } else {
+        if (m_styleResolver->hasPendingAuthorStyleSheets())

[esprehn, 2013/11/15 10:36:32]

else if

[tasak, 2013/11/18 08:30:53]

Done.

+            m_styleResolver->appendPendingAuthorStyleSheets();
+    }
+    return m_styleResolver.get();
+}
+
 void Document::createStyleResolver()
 {
     // It is a programming error to attempt to resolve style on a Document
     // which is not in a frame. Code which hits this should have checked
     // Document::isActive() before calling into code which could get here.
     ASSERT(frame());
 
     m_styleResolver = adoptPtr(new StyleResolver(*this));
-    m_styleEngine->combineCSSFeatureFlags(m_styleResolver->ruleFeatureSet());
+    m_styleEngine->combineCSSFeatureFlags(m_styleResolver->ensureRuleFeatureSet());
 }
 
 void Document::clearStyleResolver()
 {
     m_styleResolver.clear();
 }
 
 void Document::attach(const AttachContext& context)
 {
     ASSERT(m_lifecyle.state() == DocumentLifecycle::Inactive);
@@ skipping 3234 matching lines @@
 void Document::modifiedStyleSheet(StyleSheet* sheet, RecalcStyleTime when, StyleResolverUpdateMode updateMode)
 {
     if (!isActive())
         return;
 
     styleEngine()->modifiedStyleSheet(sheet);
     styleResolverChanged(when, updateMode);
 }
 
 } // namespace WebCore