Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/css/StyleRuleImport.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2005, 2006, 2008, 2009, 2010, 2012 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 54 matching lines @@
 }
 
 void StyleRuleImport::setCSSStyleSheet(
     const String& href,
     const KURL& baseURL,
     const String& charset,
     const CSSStyleSheetResource* cachedStyleSheet) {
   if (m_styleSheet)
     m_styleSheet->clearOwnerRule();
 
-  CSSParserContext context = m_parentStyleSheet
-                                 ? m_parentStyleSheet->parserContext()
-                                 : strictCSSParserContext();
-  context.setCharset(charset);
+  CSSParserContext* context = CSSParserContext::create(
+      m_parentStyleSheet ? m_parentStyleSheet->parserContext()
+                         : strictCSSParserContext(),
+      nullptr);
+  context->setCharset(charset);
   Document* document =
       m_parentStyleSheet ? m_parentStyleSheet->singleOwnerDocument() : nullptr;
   if (!baseURL.isNull()) {
-    context.setBaseURL(baseURL);
-    if (document)
-      context.setReferrer(Referrer(baseURL.strippedForUseAsReferrer(),
-                                   document->getReferrerPolicy()));
+    context->setBaseURL(baseURL);
+    if (document) {
+      context->setReferrer(Referrer(baseURL.strippedForUseAsReferrer(),
+                                    document->getReferrerPolicy()));
+    }
   }
 
   m_styleSheet = StyleSheetContents::create(this, href, context);
 
   m_styleSheet->parseAuthorStyleSheet(
       cachedStyleSheet, document ? document->getSecurityOrigin() : 0);
 
   m_loading = false;
 
   if (m_parentStyleSheet) {
@@ skipping 46 matching lines @@
     // the sheet being imported is pending.
     if (m_parentStyleSheet && m_parentStyleSheet->loadCompleted() &&
         rootSheet == m_parentStyleSheet)
       m_parentStyleSheet->startLoadingDynamicSheet();
     m_loading = true;
     m_resource->addClient(m_styleSheetClient);
   }
 }
 
 }  // namespace blink