Very simple version of Isolates.

tests/lib/async/timer_isolate_test.dart

Index: tests/lib/async/timer_isolate_test.dart
diff --git a/tests/lib/async/timer_isolate_test.dart b/tests/lib/async/timer_isolate_test.dart
index 80d2220d8230a600f5d87321df475b7d62bbac8a..31776c5f5edb009b82cdd31b7ffd5559ed05a0b0 100644
--- a/tests/lib/async/timer_isolate_test.dart
+++ b/tests/lib/async/timer_isolate_test.dart
@@ -10,11 +10,9 @@ import '../../../pkg/unittest/lib/unittest.dart';
 
 const Duration TIMEOUT = const Duration(milliseconds: 100);
 
-createTimer() {
-  port.receive((msg, replyTo) {
-    new Timer(TIMEOUT, () {
-      replyTo.send("timer_fired");
-    });
+createTimer(replyTo) {
+  new Timer(TIMEOUT, () {
+    replyTo.send("timer_fired");
   });
 }
 
@@ -23,15 +21,15 @@ main() {
     int startTime;
     int endTime;
 
-    port.receive(expectAsync2((msg, _) {
+    ReceivePort port = new ReceivePort();
+
+    port.first.then(expectAsync1((msg) {
       expect("timer_fired", msg);
       int endTime = (new DateTime.now()).millisecondsSinceEpoch;
       expect(endTime - startTime, greaterThanOrEqualTo(TIMEOUT.inMilliseconds));
-      port.close();
     }));
 
     startTime = (new DateTime.now()).millisecondsSinceEpoch;
-    var sendPort = spawnFunction(createTimer);
-    sendPort.send("sendPort", port.toSendPort());
+    var remote = Isolate.spawn(createTimer, port.sendPort);
   });
 }