StyleResolver should update RuleSets lazily.

Source/core/dom/DocumentStyleSheetCollection.cpp

Index: Source/core/dom/DocumentStyleSheetCollection.cpp
diff --git a/Source/core/dom/DocumentStyleSheetCollection.cpp b/Source/core/dom/DocumentStyleSheetCollection.cpp
index 01c32420b3026f93db400dd5fb3a402782e1f3aa..cc38e4a74fe61dfd6f9b5fcf2499ec1da4d531ed 100644
--- a/Source/core/dom/DocumentStyleSheetCollection.cpp
+++ b/Source/core/dom/DocumentStyleSheetCollection.cpp
@@ -167,10 +167,11 @@ bool DocumentStyleSheetCollection::updateActiveStyleSheets(StyleEngine* collecti
         styleResolver->setBuildScopedStyleTreeInDocumentOrder(false);
         if (styleResolverUpdateType == Reset) {
             resetAllRuleSetsInTreeScope(styleResolver);
-            styleResolver->appendAuthorStyleSheets(0, activeCSSStyleSheets);
+            styleResolver->removePendingAuthorStyleSheets(m_activeAuthorStyleSheets);
+            styleResolver->lazyAppendAuthorStyleSheets(0, activeCSSStyleSheets);
         } else {
             ASSERT(styleResolverUpdateType == Additive);
-            styleResolver->appendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), activeCSSStyleSheets);
+            styleResolver->lazyAppendAuthorStyleSheets(m_activeAuthorStyleSheets.size(), activeCSSStyleSheets);
         }
     }
     m_scopingNodesForStyleScoped.didRemoveScopingNodes();