pkg/analysis_server: fixes for unittest deprecations

pkg/analysis_server/test/analysis_server_test.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 test.analysis_server;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/domain_server.dart';
 import 'package:analysis_server/src/protocol.dart';
-import 'package:unittest/matcher.dart';
 import 'package:unittest/unittest.dart';
 
 import 'mocks.dart';
 
 main(List<String> args) {
   group('AnalysisServer', () {
     setUp(AnalysisServerTest.setUp);
 //    test('createContext', AnalysisServerTest.createContext);
     test('echo', AnalysisServerTest.echo);
     test('shutdown', AnalysisServerTest.shutdown);
@@ skipping 64 matching lines @@
   @override
   Response handleRequest(Request request) {
     if (request.method == 'echo') {
       var response = new Response(request.id);
       response.setResult('echo', true);
       return response;
     }
     return null;
   }
 }