Remove race(s) in vmservice tests.

tests/standalone/vmservice/multiple_isolate_list_script.dart

 // Copyright (c) 2013, 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 multiple_isolate_list_script;
 
 import 'dart:io';
 import 'dart:isolate';
 
 void isolateMain1() {
-  // Die immediately.
+  // Spawn another isolate.
+  spawnFunction(myIsolateName);
+  // Kill this isolate.
   port.close();
 }
 
 void myIsolateName() {
   // Stay running.
   port.receive((a, b) {
     port.close();
   });
+  print(''); // Print blank line to signal that we are ready.
 }
 
 main() {
   spawnFunction(isolateMain1);
-  spawnFunction(myIsolateName);
-  print(''); // Print blank line to signal that we are ready.
   // Wait until signaled from spawning test.
   stdin.first.then((_) => exit(0));
 }