Update test.

tests/isolate/object_leak_test.dart

 // Copyright (c) 2011, 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.
 
 // Regression test for http://dartbug.com/18942
 
 library LeakTest;
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import 'dart:isolate';
 import 'dart:async';
 
 
 class A {
   var x = 0;
 }
 
 fun(msg) {
-  print("received: ${msg.x}");
-  msg.x = 1;
-  print("done updating: ${msg.x}");
+  var a = msg[0];
+  var replyTo = msg[1];
+  print("received: ${a.x}");
+  a.x = 1;
+  print("done updating: ${a.x}");
+  replyTo.send("done");
 }
 
 main() {
   asyncStart();
   var a = new A();
-  // Sending an A object to another isolate should not work.
-  Isolate.spawn(fun, a).then((isolate) {
-    new Timer(const Duration(milliseconds: 300), () {
-      // Changes in other isolate must not reach here.
-      Expect.equals(0, a.x);
-      asyncEnd();
-    });
-  }, onError: (e) {
-    // Sending an A isn't required to work.
-    // It works in the VM, but not in dart2js.
-    print("Send of A failed:\n$e");
+  ReceivePort rp = new ReceivePort();
+  Isolate.spawn(fun, [a, rp.sendPort]);
+  rp.first.then((msg) {
+    Expect.equals("done", msg);
+    // Changes in other isolate must not reach here.
+    Expect.equals(0, a.x);
     asyncEnd();
   });
 }