StyleResolver should update RuleSets lazily.

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index 186450e231cd08a8d09d9f4ae4cdd546fefecb7e..e65c899f8d65c1b3ce0f118115449fa2942e0a0a 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -351,12 +351,6 @@ bool StyleEngine::updateActiveStyleSheets(StyleResolverUpdateMode updateMode)
                 m_activeTreeScopes.remove(*it);
         m_dirtyTreeScopes.clear();
     }
-
-    if (StyleResolver* styleResolver = m_document.styleResolverIfExists()) {
-        styleResolver->finishAppendAuthorStyleSheets();
-        resetCSSFeatureFlags(styleResolver->ruleFeatureSet());
-    }
-
     m_needsUpdateActiveStylesheetsOnStyleRecalc = false;
     activeStyleSheetsUpdatedForInspector();
     m_usesRemUnits = m_documentStyleSheetCollection.usesRemUnits();