Very simple version of Isolates.

tests/html/async_test.dart

 library async_test;
 
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:html';
 
-oneshotTimerIsolate() {
-  port.receive((msg, replyTo) {
-    expect(msg, 'START');
-    new Timer(const Duration(milliseconds: 10), () {
+oneshotTimerIsolate(message) {
+  var command = message[0];
+  var replyTo = message[1];
+  expect(command, 'START');
+  new Timer(const Duration(milliseconds: 10), () {
+    replyTo.send('DONE');
+  });
+}
+
+periodicTimerIsolate(message) {
+  var command = message[0];
+  var replyTo = message[1];
+  expect(command, 'START');
+  int counter = 0;
+  new Timer.periodic(const Duration(milliseconds: 10), (timer) {
+    if (counter == 3) {
+      counter = 1024;
+      timer.cancel();
+      // Wait some more time to be sure callback won't be invoked any
+      // more.
+      new Timer(const Duration(milliseconds: 30), () {
+        replyTo.send('DONE');
+      });
+      return;
+    }
+    assert(counter < 3);
+    counter++;
+  });
+}
+
+cancellingIsolate(message) {
+  var command = message[0];
+  var replyTo = message[1];
+  expect(command, 'START');
+  bool shot = false;
+  var oneshot;
+  var periodic;
+  periodic = new Timer.periodic(const Duration(milliseconds: 10), (timer) {
+    expect(shot, isFalse);
+    shot = true;
+    expect(timer, same(periodic));
+    periodic.cancel();
+    oneshot.cancel();
+    // Wait some more time to be sure callbacks won't be invoked any
+    // more.
+    new Timer(const Duration(milliseconds: 50), () {
       replyTo.send('DONE');
     });
   });
-}
-
-periodicTimerIsolate() {
-  port.receive((msg, replyTo) {
-    expect(msg, 'START');
-    int counter = 0;
-    new Timer.periodic(const Duration(milliseconds: 10), (timer) {
-      if (counter == 3) {
-        counter = 1024;
-        timer.cancel();
-        // Wait some more time to be sure callback won't be invoked any
-        // more.
-        new Timer(const Duration(milliseconds: 30), () {
-          replyTo.send('DONE');
-        });
-        return;
-      }
-      assert(counter < 3);
-      counter++;
-    });
+  // We launch the oneshot timer after the periodic timer. Otherwise a
+  // (very long) context switch could make this test flaky: assume the
+  // oneshot timer is created first and then there is a 30ms context switch.
+  // when the periodic timer is scheduled it would execute after the oneshot.
+  oneshot = new Timer(const Duration(milliseconds: 30), () {
+    fail('Should never be invoked');
   });
 }
 
-cancellingIsolate() {
-  port.receive((msg, replyTo) {
-    expect(msg, 'START');
-    bool shot = false;
-    var oneshot;
-    var periodic;
-    periodic = new Timer.periodic(const Duration(milliseconds: 10), (timer) {
-      expect(shot, isFalse);
-      shot = true;
-      expect(timer, same(periodic));
-      periodic.cancel();
-      oneshot.cancel();
-      // Wait some more time to be sure callbacks won't be invoked any
-      // more.
-      new Timer(const Duration(milliseconds: 50), () {
-        replyTo.send('DONE');
-      });
-    });
-    // We launch the oneshot timer after the periodic timer. Otherwise a
-    // (very long) context switch could make this test flaky: assume the
-    // oneshot timer is created first and then there is a 30ms context switch.
-    // when the periodic timer is scheduled it would execute after the oneshot.
-    oneshot = new Timer(const Duration(milliseconds: 30), () {
-      fail('Should never be invoked');
-    });
-  });
-}
-
 main() {
   useHtmlConfiguration();
 
   test('one shot timer in pure isolate', () {
-    expect(spawnFunction(oneshotTimerIsolate).call('START'),
-           completion('DONE'));
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(oneshotTimerIsolate,
+                               ['START', response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
   });
   test('periodic timer in pure isolate', () {
-    expect(spawnFunction(periodicTimerIsolate).call('START'),
-           completion('DONE'));
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(periodicTimerIsolate,
+                               ['START', response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
   });
   test('cancellation in pure isolate', () {
-    expect(spawnFunction(cancellingIsolate).call('START'),
-           completion('DONE'));
+    var response = new ReceivePort();
+    var remote = Isolate.spawn(cancellingIsolate,
+                               ['START', response.sendPort]);
+    expect(remote.then((_) => response.first), completion('DONE'));
   });
 }