Reverts VM thread cleanup

runtime/tests/vm/dart/spawn_infinite_loop_test.dart

Index: runtime/tests/vm/dart/spawn_infinite_loop_test.dart
diff --git a/runtime/tests/vm/dart/spawn_infinite_loop_test.dart b/runtime/tests/vm/dart/spawn_infinite_loop_test.dart
deleted file mode 100644
index cc0fb42d2a6ac0bac2025d903b21b0352fb0e0a8..0000000000000000000000000000000000000000
--- a/runtime/tests/vm/dart/spawn_infinite_loop_test.dart
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright (c) 2015, 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.
-
-import 'dart:isolate';
-
-// This test ensures that the VM can kill the spawned isolate during VM
-// shutdown even when the isolate is in an infinite loop and will not finish
-// on its own.
-
-void loop(msg) {
-  while (true) {}
-  throw "Unreachable";
-}
-
-void main() {
-  Isolate.spawn(loop, []);
-}