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

pkg/compiler/lib/src/parser/parser.dart

 // Copyright (c) 2012, 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 dart2js.parser;
 
 import '../common.dart';
 import '../options.dart' show ParserOptions;
 import '../tokens/keyword.dart' show Keyword;
 import '../tokens/precedence.dart' show PrecedenceInfo;
@@ skipping 462 matching lines @@
     }
     String value = token.stringValue;
     if ((identical('=', value)) || (identical(':', value))) {
       // TODO(ahe): Validate that these are only used for optional parameters.
       Token equal = token;
       token = parseExpression(token.next);
       listener.handleValuedFormalParameter(equal, token);
       if (type.isRequired) {
         listener.reportError(
             equal, MessageKind.REQUIRED_PARAMETER_WITH_DEFAULT);
-      } else if (type.isNamed && identical('=', value)) {
-        listener.reportError(equal, MessageKind.NAMED_PARAMETER_WITH_EQUALS);

[floitsch, 2016/10/11 09:37:11]

Remove that error message.

[Lasse Reichstein Nielsen, 2016/10/11 13:35:18]

Done.

       } else if (type.isPositional && identical(':', value)) {
         listener.reportError(
             equal, MessageKind.POSITIONAL_PARAMETER_WITH_EQUALS);
       }
     }
     listener.endFormalParameter(thisKeyword);
     return token;
   }
 
   Token parseOptionalFormalParameters(Token token, bool isNamed) {
@@ skipping 2512 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }