Make isolate tests work on drt (and hopefully dartium).

tests/isolate/spawn_function_test.dart

Index: tests/isolate/spawn_function_test.dart
diff --git a/tests/isolate/spawn_function_test.dart b/tests/isolate/spawn_function_test.dart
index a452477065941439bfbe97b1f06d38ec947d7b44..54cfb5a75a49b4a8d99ec3f3e9d8a5ca7ee08aa0 100644
--- a/tests/isolate/spawn_function_test.dart
+++ b/tests/isolate/spawn_function_test.dart
@@ -5,7 +5,8 @@
 // Example of spawning an isolate from a function.
 library spawn_tests;
 import 'dart:isolate';
-import '../../pkg/unittest/lib/unittest.dart';
+import 'package:unittest/unittest.dart';
+import "remote_unittest_helper.dart";
 
 child(args) {
   var msg = args[0];
@@ -13,7 +14,8 @@ child(args) {
   reply.send('re: $msg');
 }
 
-main() {
+void main([args, port]) {
+  if (testRemote(main, port)) return;
   test('message - reply chain', () {
     ReceivePort port = new ReceivePort();
     Isolate.spawn(child, ['hi', port.sendPort]);