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

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIPaintStroke.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/CSSPropertyAPIPaintStroke.h"
 
 #include "core/css/CSSURIValue.h"
 #include "core/css/CSSValue.h"
 #include "core/css/CSSValueList.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIPaintStroke::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   if (range.peek().id() == CSSValueNone)
     return CSSPropertyParserHelpers::consumeIdent(range);
-  CSSURIValue* url = CSSPropertyParserHelpers::consumeUrl(range, &context);
+  CSSURIValue* url = CSSPropertyParserHelpers::consumeUrl(range, context);
   if (url) {
     CSSValue* parsedValue = nullptr;
     if (range.peek().id() == CSSValueNone) {
       parsedValue = CSSPropertyParserHelpers::consumeIdent(range);
     } else {
       parsedValue =
-          CSSPropertyParserHelpers::consumeColor(range, context.mode());
+          CSSPropertyParserHelpers::consumeColor(range, context->mode());
     }
     if (parsedValue) {
       CSSValueList* values = CSSValueList::createSpaceSeparated();
       values->append(*url);
       values->append(*parsedValue);
       return values;
     }
     return url;
   }
-  return CSSPropertyParserHelpers::consumeColor(range, context.mode());
+  return CSSPropertyParserHelpers::consumeColor(range, context->mode());
 }
 
 }  // namespace blink