Skip ruleset invalidations for SubtreeStyleChange roots.

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 1066 matching lines @@
       treeScope.document().hasNodesWithPlaceholderStyle()) {
     treeScope.document().setNeedsStyleRecalc(
         SubtreeStyleChange, StyleChangeReasonForTracing::create(
                                 StyleChangeReason::CleanupPlaceholderStyles));
     return;
   }
 
   if (changedRuleFlags & KeyframesRules)
     ScopedStyleResolver::keyframesRulesAdded(treeScope);
 
+  Node& invalidationRoot =
+      ScopedStyleResolver::invalidationRootForTreeScope(treeScope);
+  if (invalidationRoot.getStyleChangeType() >= SubtreeStyleChange)
+    return;
+
   if (fontsChanged || (changedRuleFlags & FullRecalcRules)) {
-    ScopedStyleResolver::invalidationRootForTreeScope(treeScope)
-        .setNeedsStyleRecalc(SubtreeStyleChange,
-                             StyleChangeReasonForTracing::create(
-                                 StyleChangeReason::ActiveStylesheetsUpdate));
+    invalidationRoot.setNeedsStyleRecalc(
+        SubtreeStyleChange, StyleChangeReasonForTracing::create(
+                                StyleChangeReason::ActiveStylesheetsUpdate));
     return;
   }
 
   scheduleInvalidationsForRuleSets(treeScope, changedRuleSets);
 }
 
 const MediaQueryEvaluator& StyleEngine::ensureMediaQueryEvaluator() {
   if (!m_mediaQueryEvaluator) {
     if (document().frame())
       m_mediaQueryEvaluator = new MediaQueryEvaluator(document().frame());
@@ skipping 47 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : m_injectedAuthorStyleSheets) {
     visitor->traceWrappers(sheet);
   }
   visitor->traceWrappers(m_documentStyleSheetCollection);
 }
 
 }  // namespace blink