Change CSSParserContext to have a Document handle (vs UseCounter).

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

 /*
  * Copyright (C) 2007, 2008, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 155 matching lines @@
   Member<CSSKeyframeRule>& rule = m_childRuleCSSOMWrappers[index];
   if (!rule)
     rule = new CSSKeyframeRule(m_keyframesRule->keyframes()[index].get(),
                                const_cast<CSSKeyframesRule*>(this));
 
   return rule.get();
 }
 
 CSSKeyframeRule* CSSKeyframesRule::anonymousIndexedGetter(
     unsigned index) const {
-  if (UseCounter* useCounter = UseCounter::getFrom(parentStyleSheet()))
-    useCounter->count(UseCounter::CSSKeyframesRuleAnonymousIndexedGetter);
+  const Document* parentDocument =
+      CSSStyleSheet::singleOwnerDocument(parentStyleSheet());
+  if (parentDocument) {
+    UseCounter::count(*parentDocument,
+                      UseCounter::CSSKeyframesRuleAnonymousIndexedGetter);
+  }
   return item(index);
 }
 
 CSSRuleList* CSSKeyframesRule::cssRules() const {
   if (!m_ruleListCSSOMWrapper)
     m_ruleListCSSOMWrapper = LiveCSSRuleList<CSSKeyframesRule>::create(
         const_cast<CSSKeyframesRule*>(this));
   return m_ruleListCSSOMWrapper.get();
 }
 
 void CSSKeyframesRule::reattach(StyleRuleBase* rule) {
   ASSERT(rule);
   m_keyframesRule = toStyleRuleKeyframes(rule);
 }
 
 DEFINE_TRACE(CSSKeyframesRule) {
   CSSRule::trace(visitor);
   visitor->trace(m_childRuleCSSOMWrappers);
   visitor->trace(m_keyframesRule);
   visitor->trace(m_ruleListCSSOMWrapper);
 }
 
 }  // namespace blink