Very simple version of Isolates.

runtime/tests/vm/dart/isolate_unhandled_exception_uri_helper.dart

-// Copyright (c) 2012, 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 isolate_unhandled_exception_uri_helper;
-
-import 'dart:isolate';
-
-// Isolate script that throws an uncaught exception, which is caught by an
-// uncaught exception handler.
-
-void main() {
-  port.receive((message, replyTo) {
-    if (message == 'throw exception') {
-      replyTo.call('throwing exception');
-      throw new UnsupportedError('ignore this exception');
-    }
-    replyTo.call('hello');
-    port.close();
-  });
-}
-
-bool _unhandledExceptionCallback(IsolateUnhandledException e) {
-  return e.source.message == 'ignore this exception';
-}