Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/completion/dart/field_formal_contributor_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.services.completion.field_formal;
 
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/dart/field_formal_contributor.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../../../utils.dart';
 import 'completion_contributor_util.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(FieldFormalContributorTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(FieldFormalContributorTest);
+  });
 }
 
 @reflectiveTest
 class FieldFormalContributorTest extends DartCompletionContributorTest {
   @override
   DartCompletionContributor createContributor() {
     return new FieldFormalContributor();
   }
 
   test_ThisExpression_constructor_param() async {
@@ skipping 162 matching lines @@
           int y;
           Point({this.x, this.^}) {}
           ''');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
     expect(replacementLength, 0);
     assertSuggestField('y', 'int', relevance: DART_RELEVANCE_LOCAL_FIELD);
     assertNotSuggested('x');
   }
 }