StyleResolver should update RuleSets lazily.

Source/core/css/resolver/StyleResolver.h

Index: Source/core/css/resolver/StyleResolver.h
diff --git a/Source/core/css/resolver/StyleResolver.h b/Source/core/css/resolver/StyleResolver.h
index 51d87a6e34177017176ee62c432aa0b6ac3feb78..c651f7344022921436997ccb12a2ae437d9f8888 100644
--- a/Source/core/css/resolver/StyleResolver.h
+++ b/Source/core/css/resolver/StyleResolver.h
@@ -40,6 +40,7 @@
 #include "wtf/Deque.h"
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
+#include "wtf/ListHashSet.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 
@@ -216,6 +217,11 @@ public:
     void resetAtHostRules(const ShadowRoot*);
     void finishAppendAuthorStyleSheets();
 
+    void lazyAppendAuthorStyleSheets(unsigned firstNew, const Vector<RefPtr<CSSStyleSheet> >&);
+    void removePendingAuthorStyleSheets(const Vector<RefPtr<CSSStyleSheet> >&);
+    void appendPendingAuthorStyleSheets();
+    bool hasPendingAuthorStyleSheets() const { return m_pendingStyleSheets.size() > 0 || m_needCollectFeatures; }
+
     DocumentRuleSets& ruleSets() { return m_ruleSets; }
     const DocumentRuleSets& ruleSets() const { return m_ruleSets; }
     SelectorFilter& selectorFilter() { return m_selectorFilter; }
@@ -265,6 +271,12 @@ public:
     InspectorCSSOMWrappers& inspectorCSSOMWrappers() { return m_inspectorCSSOMWrappers; }
 
     const RuleFeatureSet& ruleFeatureSet() const { return m_features; }

[eseidel, 2013/11/06 01:39:10]

I'm confused.  This can now be stale right?  Don't all callers need to call
ensureRuleFeatureSet?

[tasak, 2013/11/06 05:42:26]

I left the method for fast-path, e.g. Document::createStyleResolver or
something.
However, I agree that it is very difficult to find which method we should use.
So I removed "ruleFeatureSet" and replaced "ruleFeatureSet" with
"ensureRuleFeatureSet"  (or just m_features in StyleResolver.cpp).

+    const RuleFeatureSet& ensureRuleFeatureSet()
+    {
+        if (hasPendingAuthorStyleSheets())
+            appendPendingAuthorStyleSheets(); // slow path.
+        return m_features;
+    }
 
     StyleSharingList& styleSharingList() { return m_styleSharingList; }
 
@@ -285,6 +297,10 @@ private:
     // FIXME: This should probably go away, folded into FontBuilder.
     void updateFont(StyleResolverState&);
 
+    void filterFontFaceAndViewportRules(const Vector<RefPtr<StyleRuleBase> >& rules, bool& needsResolveViewport);
+    void filterFontFaceAndViewportRulesFromSheet(StyleSheetContents*, bool& needsResolveViewport);
+    bool filterFontFaceAndViewportRulesFromAuthorStyleSheets(unsigned firstNew, const Vector<RefPtr<CSSStyleSheet> >& styleSheets);
+
     void collectPseudoRulesForElement(Element*, ElementRuleCollector&, PseudoId, unsigned rulesToInclude);
     void matchUARules(ElementRuleCollector&, RuleSet*);
     void matchAuthorRules(Element*, ElementRuleCollector&, bool includeEmptyRules);
@@ -295,6 +311,7 @@ private:
     void matchUserRules(ElementRuleCollector&, bool includeEmptyRules);
     void collectFeatures();
     void collectTreeBoundaryCrossingRules(ElementRuleCollector&, bool includeEmptyRules);
+    void resetRuleFeatures();
 
     bool fastRejectSelector(const RuleData&) const;
 
@@ -350,6 +367,8 @@ private:
 
     RefPtr<ViewportStyleResolver> m_viewportStyleResolver;
 
+    ListHashSet<CSSStyleSheet*, 16> m_pendingStyleSheets;
+
     ScopedStyleTree m_styleTree;
 
     // FIXME: The entire logic of collecting features on StyleResolver, as well astransferring them
@@ -357,6 +376,7 @@ private:
     RuleFeatureSet m_features;
     OwnPtr<RuleSet> m_siblingRuleSet;
     OwnPtr<RuleSet> m_uncommonAttributeRuleSet;
+    bool m_needCollectFeatures;
 
     InspectorCSSOMWrappers m_inspectorCSSOMWrappers;
 
@@ -384,6 +404,18 @@ inline bool checkRegionSelector(const CSSSelector* regionSelector, Element* regi
     return false;
 }
 
+inline bool isDocumentScope(const ContainerNode* scope)
+{
+    return !scope || scope->isDocumentNode();
+}
+
+inline void appendPendingStyleSheetsIfNeeded(StyleResolver* styleResolver)
+{
+    if (!styleResolver || !styleResolver->hasPendingAuthorStyleSheets())
+        return;
+    styleResolver->appendPendingAuthorStyleSheets();
+}
+
 } // namespace WebCore
 
 #endif // StyleResolver_h