Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/server_options_test.dart

 // Copyright (c) 2015, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library analysis_server.test.server_options;
 
 import 'package:analysis_server/src/server_options.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 import 'utils.dart';
 
 void main() {
   initializeTestEnvironment();
 
   group('server_options', () {
     test('basic - []', () {
       var options = new ServerOptions.fromContents('''# ignored
 foo: bar
-baz: padded   
+baz: padded

[Paul Berry, 2016/10/06 15:55:45]

Don't delete the end of line space here.  It's necessary for the test, because
the test is verifying that ServerOptions.fromContents properly strips the end of
line space.

[scheglov, 2016/10/06 17:17:07]

OK

I changed the code to make it resilient to formatting in
https://codereview.chromium.org/2402483002

 ''');
       expect(options['foo'], equals('bar'));
       expect(options['baz'], equals('padded'));
     });
     test('basic - isSet', () {
       var options = new ServerOptions.fromContents('''foo: true
 bar: TRUE
 baz: false
 foobar: off
 ''');
       expect(options.isSet('foo'), isTrue);
       expect(options.isSet('bar'), isTrue);
       expect(options.isSet('baz'), isFalse);
       expect(options.isSet('foobar'), isFalse);
       expect(options.isSet('does_not_exist'), isFalse);
       expect(options.isSet('does_not_exist', defaultValue: true), isTrue);
     });
 
     test('basic - getStringValue', () {
       var options = new ServerOptions.fromContents('''foo: someValue
 ''');
       expect(options.getStringValue('foo'), equals('someValue'));
       expect(options.getStringValue('not_there'), isNull);
       expect(options.getStringValue('not_there', defaultValue: 'bar'),
           equals('bar'));
     });
   });
 }