Switch 'analyzer' to 'package:test' and test_reflective_loader ^0.1.0.

pkg/analyzer/test/src/dart/element/test_all.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 analyzer.test.src.dart.element.test_all;
 
-import 'package:unittest/unittest.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../../utils.dart';
 import 'element_test.dart' as element;
 
 /// Utility for manually running all tests.
 main() {
   initializeTestEnvironment();
-  group('element tests', () {
+  defineReflectiveSuite(() {
     element.main();
-  });
+  }, name: 'element');
 }