Remove AsyncError with Expando.

tests/standalone/io/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 "package:expect/expect.dart";
@@ skipping 16 matching lines @@
 }
 
 void testInvalidBind() {
   int count = 0;
   ReceivePort port = new ReceivePort();
   port.receive((_, __) { count++; if (count == 3) port.close(); });
 
   // Bind to a unknown DNS name.
   ServerSocket.bind("ko.faar.__hest__")
       .then((_) { Expect.fail("Failure expected"); } )
-      .catchError((e) {
-        Expect.isTrue(e.error is SocketIOException);
+      .catchError((error) {
+        Expect.isTrue(error is SocketIOException);
         port.toSendPort().send(1);
       });
 
   // Bind to an unavaliable IP-address.
   ServerSocket.bind("8.8.8.8")
       .then((_) { Expect.fail("Failure expected"); } )
-      .catchError((e) {
-        Expect.isTrue(e.error is SocketIOException);
+      .catchError((error) {
+        Expect.isTrue(error is SocketIOException);
         port.toSendPort().send(1);
       });
 
   // Bind to a port already in use.
   // Either an error or a successful bind is allowed.
   // Windows platforms allow multiple binding to the same socket, with
   // unpredictable results.
   ServerSocket.bind("127.0.0.1")
       .then((s) {
         ServerSocket.bind("127.0.0.1", s.port)
             .then((t) {
               Expect.equals('windows', Platform.operatingSystem);
               Expect.equals(s.port, t.port);
               port.toSendPort().send(1);
             })
-            .catchError((e) {
+            .catchError((error) {
               Expect.notEquals('windows', Platform.operatingSystem);
-              Expect.isTrue(e.error is SocketIOException);
+              Expect.isTrue(error is SocketIOException);
               port.toSendPort().send(1);
             });
       });
 }
 
 void testConnectNoDestroy() {
   ReceivePort port = new ReceivePort();
   ServerSocket.bind().then((server) {
     server.listen((_) { });
     Socket.connect("127.0.0.1", server.port).then((_) {
@@ skipping 147 matching lines @@
   testConnectNoDestroy();
   testConnectImmediateDestroy();
   testConnectConsumerClose();
   testConnectConsumerWriteClose();
   testConnectStreamClose();
   testConnectStreamDataClose(true);
   testConnectStreamDataClose(false);
   testConnectStreamDataCloseCancel(true);
   testConnectStreamDataCloseCancel(false);
 }