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

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIQuotes.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/CSSPropertyAPIQuotes.h"
 
 #include "core/css/CSSStringValue.h"
 #include "core/css/CSSValueList.h"
 #include "core/css/parser/CSSParserContext.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIQuotes::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   if (range.peek().id() == CSSValueNone)
     return CSSPropertyParserHelpers::consumeIdent(range);
   CSSValueList* values = CSSValueList::createSpaceSeparated();
   while (!range.atEnd()) {
     CSSStringValue* parsedValue =
         CSSPropertyParserHelpers::consumeString(range);
     if (!parsedValue)
       return nullptr;
     values->append(*parsedValue);
   }
   if (values->length() && values->length() % 2 == 0)
     return values;
   return nullptr;
 }
 
 }  // namespace blink