Very simple version of Isolates.

tests/isolate/isolate_stress_test.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.
 
 // This test creates a lot of isolates.  This is meant to exhaust
 // resources if the isolates aren't closed correctly (which happened
 // in dart2js).
 
 import 'dart:async';
 import 'dart:isolate';
 
 // TODO(12588): Remove this import when we have wrapper-less testing.
 import 'dart:html';
 
-worker() {
-  port.receive((String uri, SendPort replyTo) {
-    replyTo.send('Hello from Worker');
-    port.close();
-  });
+worker(SendPort replyTo) {
+  replyTo.send('Hello from Worker');
 }
 
 main() {
   try {
     // Create a Worker to confuse broken isolate implementation in dart2js.
     new Worker('data:application/javascript,').terminate();
   } catch (e) {
     // Ignored.
   }
   var doneClosure;
   int isolateCount = 0;
   spawnMany(reply) {
     if (reply != 'Hello from Worker') {
       throw new Exception('Unexpected reply from worker: $reply');
     }
     if (++isolateCount > 200) {
-      port.close();
       window.postMessage('unittest-suite-success', '*');
       return;
     }
-    spawnFunction(worker).call('').then(spawnMany);
+    ReceivePort response = new ReceivePort();
+    var remote = Isolate.spawn(worker, response.sendPort);
+    remote.then((_) => response.first).then(spawnMany);
     print('isolateCount = $isolateCount');
   }
 
   spawnMany('Hello from Worker');
   window.postMessage('unittest-suite-wait-for-done', '*');
 }