Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIOffsetPosition.cpp

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/properties/CSSPropertyAPIOffsetPosition.h"
 
 #include "core/css/CSSValuePair.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 #include "core/frame/UseCounter.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIOffsetPosition::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   CSSValueID id = range.peek().id();
   if (id == CSSValueAuto)
     return CSSPropertyParserHelpers::consumeIdent(range);
   CSSValue* value = CSSPropertyParserHelpers::consumePosition(
-      range, context.mode(), CSSPropertyParserHelpers::UnitlessQuirk::Forbid);
+      range, context->mode(), CSSPropertyParserHelpers::UnitlessQuirk::Forbid);
 
   // Count when we receive a valid position other than 'auto'.
-  if (context.useCounter() && value && value->isValuePair())
-    context.useCounter()->count(UseCounter::CSSOffsetInEffect);
+  if (context->isUseCounterRecordingEnabled() && value && value->isValuePair())
+    context->useCounter()->count(UseCounter::CSSOffsetInEffect);
   return value;
 }
 
 }  // namespace blink