Revert of Changed CSSParserContext argument from * to & for null safety.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIJustifyItems.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/CSSPropertyAPIJustifyItems.h"
 
 #include "core/css/CSSValuePair.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 #include "core/css/properties/CSSPropertyAlignmentUtils.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIJustifyItems::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   DCHECK(RuntimeEnabledFeatures::cssGridLayoutEnabled());
   CSSParserTokenRange rangeCopy = range;
   CSSIdentifierValue* legacy =
       CSSPropertyParserHelpers::consumeIdent<CSSValueLegacy>(rangeCopy);
   CSSIdentifierValue* positionKeyword =
       CSSPropertyParserHelpers::consumeIdent<CSSValueCenter, CSSValueLeft,
                                              CSSValueRight>(rangeCopy);
   if (!legacy)
     legacy = CSSPropertyParserHelpers::consumeIdent<CSSValueLegacy>(rangeCopy);
   if (legacy && positionKeyword) {
     range = rangeCopy;
     return CSSValuePair::create(legacy, positionKeyword,
                                 CSSValuePair::DropIdenticalValues);
   }
   return CSSPropertyAlignmentUtils::consumeSelfPositionOverflowPosition(range);
 }
 
 }  // namespace blink