Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/analysis/navigation_collector_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.
 
 library test.analysis.navigation_collector;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/domains/analysis/navigation.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(NavigationCollectorImplTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(NavigationCollectorImplTest);
+  });
 }
 
 @reflectiveTest
 class NavigationCollectorImplTest {
   NavigationCollectorImpl collector = new NavigationCollectorImpl();
 
   void test_multipleTargets() {
     collector.addRegion(
         10, 5, ElementKind.CLASS, new Location('file', 11, 12, 13, 14));
     collector.addRegion(
@@ skipping 44 matching lines @@
       expect(region.length, 20);
       expect(region.targets, hasLength(1));
       {
         NavigationTarget target = collector.targets[region.targets[0]];
         expect(target.offset, 21);
         expect(target.length, 22);
       }
     }
   }
 }