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

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIGridAutoFlow.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/CSSPropertyAPIGridAutoFlow.h"
 
 #include "core/css/CSSIdentifierValue.h"
 #include "core/css/CSSValueList.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIGridAutoFlow::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   DCHECK(RuntimeEnabledFeatures::cssGridLayoutEnabled());
   CSSIdentifierValue* rowOrColumnValue =
       CSSPropertyParserHelpers::consumeIdent<CSSValueRow, CSSValueColumn>(
           range);
   CSSIdentifierValue* denseAlgorithm =
       CSSPropertyParserHelpers::consumeIdent<CSSValueDense>(range);
   if (!rowOrColumnValue) {
     rowOrColumnValue =
         CSSPropertyParserHelpers::consumeIdent<CSSValueRow, CSSValueColumn>(
             range);
     if (!rowOrColumnValue && !denseAlgorithm)
       return nullptr;
   }
   CSSValueList* parsedValues = CSSValueList::createSpaceSeparated();
   if (rowOrColumnValue)
     parsedValues->append(*rowOrColumnValue);
   if (denseAlgorithm)
     parsedValues->append(*denseAlgorithm);
   return parsedValues;
 }
 
 }  // namespace blink