Update dart:io tests to use asyncStart/asyncEnd

tests/standalone/io/socket_close_test.dart

 // Copyright (c) 2013, 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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 //
 // Test socket close events.
 
-import "package:expect/expect.dart";
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
+import "package:async_helper/async_helper.dart";
+import "package:expect/expect.dart";
+
 const SERVERSHUTDOWN = -1;
 const ITERATIONS = 10;
 
 
 class SocketClose {
 
-  SocketClose.start(this._mode, this._donePort)
+  SocketClose.start(this._mode, this._done)
       : _receivePort = new ReceivePort(),
         _sendPort = null,
         _readBytes = 0,
         _dataEvents = 0,
         _closeEvents = 0,
         _errorEvents = 0,
         _iterations = 0 {
     _sendPort = spawnFunction(startSocketCloseServer);
     initialize();
   }
@@ skipping 109 matching lines @@
     _receivePort.receive((var message, SendPort replyTo) {
       _port = message;
       proceed();
     });
     _sendPort.send(_mode, _receivePort.toSendPort());
   }
 
   void shutdown() {
     _sendPort.send(SERVERSHUTDOWN, _receivePort.toSendPort());
     _receivePort.receive((message, ignore) {
-      _donePort.send(null);
+      _done();
       _receivePort.close();
     });
 
     switch (_mode) {
       case 0:
       case 1:
         Expect.equals(0, _dataEvents);
         Expect.equals(ITERATIONS, _closeEvents);
         break;
       case 2:
@@ skipping 20 matching lines @@
   int _port;
   ReceivePort _receivePort;
   SendPort _sendPort;
   List<int> _buffer;
   int _readBytes;
   int _dataEvents;
   int _closeEvents;
   int _errorEvents;
   int _iterations;
   int _mode;
-  SendPort _donePort;
+  Function _done;
 }
 
 
 class ConnectionData {
   ConnectionData(Socket this.connection) : readBytes = 0;
   Socket connection;
   int readBytes;
 }
 
 
@@ skipping 164 matching lines @@
 main() {
   // Run the close test in these different "modes".
   // 0: Client closes without sending at all.
   // 1: Client sends and destroys.
   // 2: Client sends. Server destroys.
   // 3: Client sends. Server responds and destroys.
   // 4: Client sends and half-closes. Server responds and destroys.
   // 5: Client sends. Server responds and half closes.
   // 6: Client sends and half-closes. Server responds and half closes.
   var tests = 7;
-  var port = new ReceivePort();
-  var completed = 0;
-  port.receive((message, ignore) {
-    if (++completed == tests) port.close();
-  });
   for (var i = 0; i < tests; i++) {
-    new SocketClose.start(i, port.toSendPort());
+    asyncStart();
+    new SocketClose.start(i, asyncEnd);
   }
 }