pkg/(unit)test: include a copy of old matcher

lib/src/simple_configuration.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 unittest.simple_configuration;
 
 import 'dart:isolate';
 
-import 'package:matcher/matcher.dart'
+import 'matcher.dart'
     show DefaultFailureHandler, configureExpectFailureHandler, TestFailure;
 
 import '../unittest.dart';
 import 'internal_test_case.dart';
 import 'utils.dart';
 
 // A custom failure handler for [expect] that routes failures to the
 // [SimpleConfiguration].
 class _ExpectFailureHandler extends DefaultFailureHandler {
   final SimpleConfiguration _config;
@@ skipping 178 matching lines @@
       }
     }
   }
 
   void _postMessage(String message) {
     // In dart2js browser tests, the JavaScript-based test controller
     // intercepts calls to print and listens for "secret" messages.
     print(message);
   }
 }