Remove AsyncError with Expando.

tests/standalone/io/socket_exception_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.
 //
 // Tests socket exceptions.
 
 import "package:expect/expect.dart";
 import "dart:async";
 import "dart:isolate";
 import "dart:io";
@@ skipping 146 matching lines @@
       var completer = new Completer();
       server.listen((socket) {
         completer.future.then((_) => socket.destroy());
       });
       Socket.connect("127.0.0.1", server.port).then((client) {
         const int SIZE = 1024 * 1024;
         int errors = 0;
         client.listen(
             (data) => Expect.fail("Unexpected data"),
             onError: (error) {
-              Expect.isTrue(error.error is SocketIOException);
+              Expect.isTrue(error is SocketIOException);
               errors++;
             },
             onDone: () {
               // We get either a close or an error followed by a close
               // on the socket.  Whether we get both depends on
               // whether the system notices the error for the read
               // event or only for the write event.
               Expect.isTrue(errors <= 1);
               server.close();
             });
         client.add(new List.filled(SIZE, 0));
         // Destroy other socket now.
         completer.complete(null);
         var port = new ReceivePort();
         client.done.then(
             (_) {
               Expect.fail("Expected error");
             },
             onError: (error) {
-              Expect.isTrue(error.error is SocketIOException);
+              Expect.isTrue(error is SocketIOException);
               port.close();
             });
       });
     });
   }
 
   static void clientSocketAddCloseResultErrorTest() {
     ServerSocket.bind().then((server) {
       var completer = new Completer();
       server.listen((socket) {
@@ skipping 35 matching lines @@
     clientSocketAddCloseErrorTest();
     clientSocketAddCloseResultErrorTest();
     unknownHostTest();
   }
 }
 
 main() {
   SocketExceptionTest.testMain();
 }