Fix socket to report write errors async.

tests/standalone/io/raw_socket_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
 
 import "dart:async";
@@ skipping 390 matching lines @@
 }
 
 void testSocketZoneError() {
   asyncStart();
   Expect.equals(Zone.ROOT, Zone.current);
   runZoned(() {
     Expect.notEquals(Zone.ROOT, Zone.current);
     RawServerSocket.bind(InternetAddress.LOOPBACK_IP_V4, 0).then((server) {
       Expect.notEquals(Zone.ROOT, Zone.current);
       server.listen((socket) {
+        Expect.notEquals(Zone.ROOT, Zone.current);
+        var timer;
+        void write() {
+          socket.write(const [0]);
+          timer = new Timer(const Duration(milliseconds: 5), write);
+        }
+        write();
         socket.listen((_) {
         }, onError: (error) {
+          timer.cancel();
           Expect.notEquals(Zone.ROOT, Zone.current);
           socket.close();
           server.close();
           throw error;
         });
-        Expect.notEquals(Zone.ROOT, Zone.current);
-        socket.write(const [0]);
       });
       RawSocket.connect("127.0.0.1", server.port).then((socket) {
         socket.close();
       });
     });
   }, onError: (e) {
     asyncEnd();
   });
 }
 
 main() {
   asyncStart();
   testArguments();
   testSimpleBind();
   testCloseOneEnd("client");
   testCloseOneEnd("server");
   testInvalidBind();
   testSimpleConnect();
   testServerListenAfterConnect();
   testSimpleReadWrite(dropReads: false);
   testSimpleReadWrite(dropReads: true);
   testPauseServerSocket();
   testPauseSocket();
   testSocketZone();
   testSocketZoneError();
   asyncEnd();
 }