Use resident compiler to start test runner (#4174)

tool/test.dart

diff --git a/tool/test.dart b/tool/test.dart
index 2eb8adc..5f1c9db 100755
--- a/tool/test.dart
+++ b/tool/test.dart
@@ -1,4 +1,4 @@
-#!/usr/bin/env dart
+#!/usr/bin/env -S dart run -r
 // Copyright (c) 2012, 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.