Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIClip.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/CSSPropertyAPIClip.h"
 
 #include "core/css/CSSQuadValue.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 
 namespace blink {
 
 namespace {
 
 CSSValue* consumeClipComponent(CSSParserTokenRange& range,
                                CSSParserMode cssParserMode) {
   if (range.peek().id() == CSSValueAuto)
     return CSSPropertyParserHelpers::consumeIdent(range);
   return CSSPropertyParserHelpers::consumeLength(
       range, cssParserMode, ValueRangeAll,
       CSSPropertyParserHelpers::UnitlessQuirk::Allow);
 }
 
 }  // namespace
 
 const CSSValue* CSSPropertyAPIClip::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   if (range.peek().id() == CSSValueAuto)
     return CSSPropertyParserHelpers::consumeIdent(range);
 
   if (range.peek().functionId() != CSSValueRect)
     return nullptr;
 
   CSSParserTokenRange args = CSSPropertyParserHelpers::consumeFunction(range);
   // rect(t, r, b, l) || rect(t r b l)
-  CSSValue* top = consumeClipComponent(args, context.mode());
+  CSSValue* top = consumeClipComponent(args, context->mode());
   if (!top)
     return nullptr;
   bool needsComma =
       CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args);
-  CSSValue* right = consumeClipComponent(args, context.mode());
+  CSSValue* right = consumeClipComponent(args, context->mode());
   if (!right ||
       (needsComma &&
        !CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args)))
     return nullptr;
-  CSSValue* bottom = consumeClipComponent(args, context.mode());
+  CSSValue* bottom = consumeClipComponent(args, context->mode());
   if (!bottom ||
       (needsComma &&
        !CSSPropertyParserHelpers::consumeCommaIncludingWhitespace(args)))
     return nullptr;
-  CSSValue* left = consumeClipComponent(args, context.mode());
+  CSSValue* left = consumeClipComponent(args, context->mode());
   if (!left || !args.atEnd())
     return nullptr;
   return CSSQuadValue::create(top, right, bottom, left,
                               CSSQuadValue::SerializeAsRect);
 }
 
 }  // namespace blink