RuleSet invalidations on single feature only, including tags.

third_party/WebKit/Source/core/dom/Document.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 1689 matching lines @@
 
 bool Document::hasPendingForcedStyleRecalc() const {
   return hasPendingVisualUpdate() && !inStyleRecalc() &&
          getStyleChangeType() >= SubtreeStyleChange;
 }
 
 void Document::updateStyleInvalidationIfNeeded() {
   DCHECK(isActive());
   ScriptForbiddenScope forbidScript;
 
-  if (!childNeedsStyleInvalidation())
+  if (!childNeedsStyleInvalidation() && !needsStyleInvalidation())
     return;
   TRACE_EVENT0("blink", "Document::updateStyleInvalidationIfNeeded");
   styleEngine().styleInvalidator().invalidate(*this);
 }
 
 void Document::setupFontBuilder(ComputedStyle& documentStyle) {
   FontBuilder fontBuilder(*this);
   CSSFontSelector* selector = styleEngine().fontSelector();
   fontBuilder.createFontForDocument(selector, documentStyle);
 }
@@ skipping 4859 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif