Don't update global ruleset when active style is dirty.

third_party/WebKit/Source/core/dom/StyleEngine.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.
@@ skipping 337 matching lines @@
 
 bool StyleEngine::needsActiveStyleUpdate() const {
   return (m_viewportResolver && m_viewportResolver->needsUpdate()) ||
          needsActiveStyleSheetUpdate() || m_globalRuleSet.isDirty();
 }
 
 void StyleEngine::updateActiveStyle() {
   DCHECK(document().isActive());
   updateViewport();
   updateActiveStyleSheets();
-  m_globalRuleSet.update(document());
+  updateGlobalRuleSet();
 }
 
 const ActiveStyleSheetVector StyleEngine::activeStyleSheetsForInspector() {
   if (document().isActive())
     updateActiveStyle();
 
   if (m_activeTreeScopes.isEmpty())
     return documentStyleSheetCollection().activeAuthorStyleSheets();
 
   ActiveStyleSheetVector activeStyleSheets;
@@ skipping 555 matching lines @@
 
 void StyleEngine::setHttpDefaultStyle(const String& content) {
   setPreferredStylesheetSetNameIfNotSet(content);
 }
 
 void StyleEngine::ensureUAStyleForFullscreen() {
   if (m_globalRuleSet.hasFullscreenUAStyle())
     return;
   CSSDefaultStyleSheets::instance().ensureDefaultStyleSheetForFullscreen();
   m_globalRuleSet.markDirty();
-  m_globalRuleSet.update(document());
+  updateActiveStyle();
 }
 
 void StyleEngine::ensureUAStyleForElement(const Element& element) {
   if (CSSDefaultStyleSheets::instance().ensureDefaultStyleSheetsForElement(
           element)) {
     m_globalRuleSet.markDirty();
-    m_globalRuleSet.update(document());
+    updateActiveStyle();
   }
 }
 
 bool StyleEngine::hasRulesForId(const AtomicString& id) const {
   return m_globalRuleSet.ruleFeatureSet().hasSelectorForId(id);
 }
 
 void StyleEngine::initialViewportChanged() {
   if (m_viewportResolver)
     m_viewportResolver->initialViewportChanged();
@@ skipping 192 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : m_injectedAuthorStyleSheets) {
     visitor->traceWrappers(sheet);
   }
   visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 }  // namespace blink