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

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIClipPath.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/CSSPropertyAPIClipPath.h"
 
 #include "core/css/CSSURIValue.h"
 #include "core/css/parser/CSSPropertyParserHelpers.h"
 #include "core/css/properties/CSSPropertyShapeUtils.h"
 
 namespace blink {
 
 const CSSValue* CSSPropertyAPIClipPath::parseSingleValue(
     CSSParserTokenRange& range,
-    const CSSParserContext& context) {
+    const CSSParserContext* context) {
   if (range.peek().id() == CSSValueNone)
     return CSSPropertyParserHelpers::consumeIdent(range);
-  if (CSSURIValue* url = CSSPropertyParserHelpers::consumeUrl(range, &context))
+  if (CSSURIValue* url = CSSPropertyParserHelpers::consumeUrl(range, context))
     return url;
-  return CSSPropertyShapeUtils::consumeBasicShape(range, &context);
+  return CSSPropertyShapeUtils::consumeBasicShape(range, context);
 }
 
 }  // namespace blink