Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/integration/analysis/update_content_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.integration.analysis.update.content;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../../utils.dart';
 import '../integration_tests.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(Test);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(Test);
+  });
 }
 
 @reflectiveTest
 class Test extends AbstractAnalysisServerIntegrationTest {
   test_updateContent() {
     String pathname = sourcePath('test.dart');
     String goodText = r'''
 main() {
   print("Hello, world!");
 }''';
@@ skipping 34 matching lines @@
               {pathname: new RemoveContentOverlay()});
         })
         .then((result) => analysisFinished)
         .then((_) {
           // Now there should be errors again, because the contents on disk are no
           // longer overridden.
           expect(currentAnalysisErrors[pathname], isNotEmpty);
         });
   }
 }