StyleResolver should update RuleSets lazily.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index a9f5313e46dd9327c41c245a8535b97d43bf4e7e..9e9c90e2e6aba0cb6c9f76e1781bfc17f098528b 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1751,7 +1751,7 @@ void Document::recalcStyle(StyleRecalcChange change)
 
         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();
         }
     }
@@ -1960,6 +1960,17 @@ void Document::setIsViewSource(bool isViewSource)
     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
@@ -1968,7 +1979,7 @@ void Document::createStyleResolver()
     ASSERT(frame());
 
     m_styleResolver = adoptPtr(new StyleResolver(*this));
-    m_styleEngine->combineCSSFeatureFlags(m_styleResolver->ruleFeatureSet());
+    m_styleEngine->combineCSSFeatureFlags(m_styleResolver->ensureRuleFeatureSet());
 }
 
 void Document::clearStyleResolver()