Do not keep InvalidationSets on the Oilpan heap.

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.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 383 matching lines @@
 
 void StyleEngine::createResolver()
 {
     TRACE_EVENT1("blink", "StyleEngine::createResolver", "frame", document().frame());
     // It is a programming error to attempt to resolve style on a Document
     // which is not in a frame. Code which hits this should have checked
     // Document::isActive() before calling into code which could get here.
 
     ASSERT(document().frame());
 
-    m_resolver = adoptPtrWillBeNoop(new StyleResolver(*m_document));
+    m_resolver = StyleResolver::create(*m_document);
 
     // A scoped style resolver for document will be created during
     // appendActiveAuthorStyleSheets if needed.
     appendActiveAuthorStyleSheets();
     combineCSSFeatureFlags(m_resolver->ensureUpdatedRuleFeatureSet());
 }
 
 void StyleEngine::clearResolver()
 {
     ASSERT(!document().inStyleRecalc());
@@ skipping 311 matching lines @@
     visitor->trace(m_dirtyTreeScopes);
     visitor->trace(m_activeTreeScopes);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
 #endif
     CSSFontSelectorClient::trace(visitor);
 }
 
 }