Unbreak local browser testing.

tools/testing/dart/vendored_pkg/args/src/parser.dart

 // Copyright (c) 2013, 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 args.src.parser;
 
 import '../args.dart';
 
 final _SOLO_OPT = new RegExp(r'^-([a-zA-Z0-9])$');
 final _ABBR_OPT = new RegExp(r'^-([a-zA-Z0-9]+)(.*)$');
@@ skipping 261 matching lines @@
           '"$value" is not an allowed value for option "${option.name}".');
     }
 
     if (option.allowMultiple) {
       results[option.name].add(value);
     } else {
       results[option.name] = value;
     }
   }
 }