Migrate a single test_all file

Change-Id: I03436dad857908f03d1bd872cd63e391cd92ac9f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/195660
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analysis_server/test/tool/test_all.dart b/pkg/analysis_server/test/tool/test_all.dart
index 4852a64..8d2910e 100644
--- a/pkg/analysis_server/test/tool/test_all.dart
+++ b/pkg/analysis_server/test/tool/test_all.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'completion_metrics/test_all.dart' as completion_metrics;