Clean up isolate tests.

tests/isolate/spawn_uri_vm_negative_test.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.
-
-// Negative test to make sure that we are reaching all assertions.
-// Note: the following comment is used by test.dart to additionally compile the
-// other isolate's code.
-// OtherScripts=spawn_uri_child_isolate.dart
-library spawn_tests;
-import 'dart:isolate';
-import '../../pkg/unittest/lib/unittest.dart';
-
-main() {
-  test('isolate fromUri - negative test', () {
-    ReceivePort port = new ReceivePort();
-    port.first.then(expectAsync1((msg) {
-      expect(msg, equals('re: hello')); // should be hi, not hello
-    }));
-
-    Isolate.spawnUri(Uri.parse('spawn_uri_child_isolate.dart'),
-                     ['hi'], port.sendPort);
-  });
-}