Clean up isolate tests.

tests/isolate/simple_message_test.dart

Index: tests/isolate/simple_message_test.dart
diff --git a/tests/isolate/isolate_negative_test.dart b/tests/isolate/simple_message_test.dart
similarity index 55%
rename from tests/isolate/isolate_negative_test.dart
rename to tests/isolate/simple_message_test.dart
index e40d23e995d9f303bea93fd33cc778f941628e8d..8338bd6eaa4d80a5c470dd9cef9350b87c6c0781 100644
--- a/tests/isolate/isolate_negative_test.dart
+++ b/tests/isolate/simple_message_test.dart
@@ -7,18 +7,20 @@
 library IsolateNegativeTest;
 import "package:expect/expect.dart";
 import 'dart:isolate';
-import '../../pkg/unittest/lib/unittest.dart';
+import "package:async_helper/async_helper.dart";
 
 void entry(SendPort replyTo) {
-  replyTo.send("foo");
+  var message = "foo";
+  message = "bar";  /// 01: runtime error
+  replyTo.send(message);
 }
 
 main() {
-  test("ensure isolate code is executed", () {
-    ReceivePort response = new ReceivePort();
-    Isolate.spawn(entry, response.sendPort);
-    response.first.then(expectAsync1((message) {
-      expect("Expected fail", isTrue);   // <=-------- Should fail here.
-    }));
+  asyncStart();
+  ReceivePort response = new ReceivePort();
+  Isolate.spawn(entry, response.sendPort);
+  response.first.then((message) {
+    Expect.equals("foo", message);
+    asyncEnd();
   });
 }