unittest step 3 and 4: remove TestFramework.dart, make test.dart use

tests/isolate/src/APIv2_spawnStandaloneTest.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.
-
-// Example of spawning an isolate from a function.
-#library('spawn_tests');
-#import('dart:isolate');
-
-child() {
-  port.receive((msg, reply) => reply.send('re: $msg'));
-}
-
-main() {
-  ReceivePort port = new ReceivePort();
-  port.receive((msg, _) {
-    Expect.equals('re: hi', msg);
-    port.close();
-  });
-
-  SendPort s = spawnFunction(child);
-  s.send('hi', port.toSendPort());
-}