Make CSSParserContext be garbage collected.

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

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2005, 2006, 2008, 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 37 matching lines @@
   const CSSSelector* selector = m_pageRule->selector();
   if (selector) {
     String pageSpecification = selector->selectorText();
     if (!pageSpecification.isEmpty())
       text.append(pageSpecification);
   }
   return text.toString();
 }
 
 void CSSPageRule::setSelectorText(const String& selectorText) {
-  CSSParserContext context(parserContext(), nullptr);
+  CSSParserContext* context =
+      CSSParserContext::create(parserContext(), nullptr);
   CSSSelectorList selectorList = CSSParser::parsePageSelector(
       context, parentStyleSheet() ? parentStyleSheet()->contents() : nullptr,
       selectorText);
   if (!selectorList.isValid())
     return;
 
   CSSStyleSheet::RuleMutationScope mutationScope(this);
 
   m_pageRule->wrapperAdoptSelectorList(std::move(selectorList));
 }
@@ skipping 21 matching lines @@
     m_propertiesCSSOMWrapper->reattach(m_pageRule->mutableProperties());
 }
 
 DEFINE_TRACE(CSSPageRule) {
   visitor->trace(m_pageRule);
   visitor->trace(m_propertiesCSSOMWrapper);
   CSSRule::trace(visitor);
 }
 
 }  // namespace blink