Update dart:io tests to use asyncStart/asyncEnd

tests/standalone/io/web_socket_protocol_processor_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.
 
-import "package:expect/expect.dart";
 import "dart:convert";
 import "dart:math";
 import "dart:async";
 import "dart:collection";
 import "dart:typed_data";
 import "dart:isolate";
 
+import "package:async_helper/async_helper.dart";
+import "package:expect/expect.dart";
+
 part '../../../sdk/lib/io/common.dart';
 part "../../../sdk/lib/io/http.dart";
 part "../../../sdk/lib/io/bytes_builder.dart";
 part "../../../sdk/lib/io/io_sink.dart";
 part "../../../sdk/lib/io/string_transformer.dart";
 part "../../../sdk/lib/io/websocket.dart";
 part "../../../sdk/lib/io/websocket_impl.dart";
 
 class WebSocketFrame {
   WebSocketFrame(int opcode, List<int> data);
@@ skipping 202 matching lines @@
   runTest(120, 130, 1);
   runTest(0, 1000, 100);
   runTest(65534, 65537, 1);
   print("Fragment messages test, messages $messageCount, frames $frameCount");
   Expect.equals(messageCount, mc.messageCount);
 }
 
 void testUnmaskedMessage() {
   var transformer = new _WebSocketProtocolTransformer(true);
   var controller = new StreamController(sync: true);
-  var port = new ReceivePort();
+  asyncStart();
   controller.stream.transform(transformer).listen((_) {}, onError: (e) {
-    port.close();
+    asyncEnd();
   });
   var message = new Uint8List(10);
   List<int> frame = createFrame(
       true, FRAME_OPCODE_BINARY, null, message, 0, message.length);
   controller.add(frame);
 }
 
 
 void main() {
   testFullMessages();
   testFragmentedMessages();
   testUnmaskedMessage();
 }