Add `=` as default-value separator for named parameters.

pkg/analyzer/lib/error/error.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.error.error;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/listener.dart';
@@ skipping 780 matching lines @@
     ParserErrorCode.STATIC_SETTER_WITHOUT_BODY,
     ParserErrorCode.STATIC_TOP_LEVEL_DECLARATION,
     ParserErrorCode.SWITCH_HAS_CASE_AFTER_DEFAULT_CASE,
     ParserErrorCode.SWITCH_HAS_MULTIPLE_DEFAULT_CASES,
     ParserErrorCode.TOP_LEVEL_OPERATOR,
     ParserErrorCode.TYPEDEF_IN_CLASS,
     ParserErrorCode.UNEXPECTED_TERMINATOR_FOR_PARAMETER_GROUP,
     ParserErrorCode.UNEXPECTED_TOKEN,
     ParserErrorCode.WITH_BEFORE_EXTENDS,
     ParserErrorCode.WITH_WITHOUT_EXTENDS,
-    ParserErrorCode.WRONG_SEPARATOR_FOR_NAMED_PARAMETER,
     ParserErrorCode.WRONG_SEPARATOR_FOR_POSITIONAL_PARAMETER,
     ParserErrorCode.WRONG_TERMINATOR_FOR_PARAMETER_GROUP,
     ParserErrorCode.VAR_AND_TYPE,
     ParserErrorCode.VAR_AS_TYPE_NAME,
     ParserErrorCode.VAR_CLASS,
     ParserErrorCode.VAR_ENUM,
     ParserErrorCode.VAR_RETURN_TYPE,
     ParserErrorCode.VAR_TYPEDEF,
     ParserErrorCode.VOID_PARAMETER,
     ParserErrorCode.VOID_VARIABLE,
@@ skipping 298 matching lines @@
 
   @override
   int get hashCode => ordinal;
 
   @override
   int compareTo(ErrorType other) => ordinal - other.ordinal;
 
   @override
   String toString() => name;
 }