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

tests/isolate/spawn_function_custom_class_test.dart

Index: tests/isolate/spawn_function_custom_class_test.dart
diff --git a/tests/isolate/spawn_function_custom_class_test.dart b/tests/isolate/spawn_function_custom_class_test.dart
index 9e83b6fcdce6dfa59a37ca7b43b9741e0b2a07e1..75c992df187aa36284db8fdffed1dc5e3ef6a287 100644
--- a/tests/isolate/spawn_function_custom_class_test.dart
+++ b/tests/isolate/spawn_function_custom_class_test.dart
@@ -9,7 +9,8 @@
 
 library spawn_tests;
 import 'dart:isolate';
-import '../../pkg/unittest/lib/unittest.dart';
+import 'package:unittest/unittest.dart';
+import "remote_unittest_helper.dart";
 
 class MyClass {
   var myVar = 'there';
@@ -24,7 +25,8 @@ child(args) {
   reply.send('re: ${new MyClass().myFunc(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]);