Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/integration/integration_tests.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.integration.analysis;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:path/path.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 import 'integration_test_methods.dart';
 import 'protocol_matchers.dart';
 
 const Matcher isBool = const isInstanceOf<bool>();
 
 const Matcher isInt = const isInstanceOf<int>();
 
 const Matcher isNotification = const MatchesJsonObject(
     'notification', const {'event': isString},
@@ skipping 894 matching lines @@
   void populateMismatches(item, List<MismatchDescriber> mismatches);
 
   /**
    * Create a [MismatchDescriber] describing a mismatch with a simple string.
    */
   MismatchDescriber simpleDescription(String description) =>
       (Description mismatchDescription) {
         mismatchDescription.add(description);
       };
 }