Implement spawnFunction from the new isolate api.

lib/isolate/isolate_api.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.
 
+class IsolateSpawnException implements Exception {

[Siggi Cherem (dart-lang), 2012/03/13 23:00:14]

(nit): move this to the bottom, so that the top of this file contains the common
APIs that people will use. 
also + a 1-line comment so that it gets documented for api.dartlang.com

+  const IsolateSpawnException(String this._s);
+  String toString() => "IsolateSpawnException: '$_s'";
+  final String _s;
+}
+
 /**
  * The initial [ReceivePort] available by default for this isolate. This
  * [ReceivePort] is created automatically and it is commonly used to establish
  * the first communication between isolates (see [spawnFunction] and
  * [spawnUri]).
  */
 ReceivePort get port() => _port;
 
 /**
  * Creates and spawns an isolate that shares the same code as the current
@@ skipping 201 matching lines @@
   /**
    * When isolates are created, an instance of the template's class is
    * instantiated in the new isolate. After the [port] has been set up, this
    * [main] method is invoked on the instance.
    */
   abstract void main();
 
   final bool _isLight;
   ReceivePort _port;
 }