Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/plugin/protocol_dart_test.dart

Index: pkg/analysis_server/test/plugin/protocol_dart_test.dart
diff --git a/pkg/analysis_server/test/plugin/protocol_dart_test.dart b/pkg/analysis_server/test/plugin/protocol_dart_test.dart
index ef2cd5089f09765e73821548688ef151f7bb8257..df1feddace1516307ea907364b4bee65b0eb553d 100644
--- a/pkg/analysis_server/test/plugin/protocol_dart_test.dart
+++ b/pkg/analysis_server/test/plugin/protocol_dart_test.dart
@@ -15,16 +15,18 @@ import 'package:analyzer/src/dart/ast/utilities.dart' as engine;
 import 'package:analyzer/src/dart/element/element.dart' as engine;
 import 'package:analyzer/src/error/codes.dart' as engine;
 import 'package:analyzer/src/generated/source.dart' as engine;
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../abstract_context.dart';
 import '../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(ElementTest);
-  defineReflectiveTests(ElementKindTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(ElementTest);
+    defineReflectiveTests(ElementKindTest);
+  });
 }
 
 @reflectiveTest