Remove AsyncError with Expando.

tests/standalone/io/http_10_test.dart

 // (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";
 import "dart:isolate";
 import "dart:io";
 
 // Client makes a HTTP 1.0 request without connection keep alive. The
 // server sets a content length but still needs to close the
 // connection as there is no keep alive.
 void testHttp10NoKeepAlive() {
   HttpServer.bind().then((server) {
     server.listen(
         (HttpRequest request) {
           Expect.isNull(request.headers.value('content-length'));
           Expect.equals(-1, request.contentLength);
           var response = request.response;
           response.contentLength = 1;
           Expect.equals("1.0", request.protocolVersion);
           response.done
               .then((_) => Expect.fail("Unexpected response completion"))
-              .catchError((e) => Expect.isTrue(e.error is HttpException));
+              .catchError((error) => Expect.isTrue(error is HttpException));
           response.write("Z");
           response.write("Z");
           response.close();
           Expect.throws(() => response.write("x"),
                         (e) => e is StateError);
         },
-        onError: (e) => Expect.fail("Unexpected error $e"));
+        onError: (e) {
+          String msg = "Unexpected error $e";
+          var trace = getAttachedStackTrace(e);
+          if (trace != null) msg += "\nStackTrace: $trace";
+          Expect.fail(msg);
+        });
 
     int count = 0;
     makeRequest() {
       Socket.connect("127.0.0.1", server.port).then((socket) {
           socket.write("GET / HTTP/1.0\r\n\r\n");
 
           List<int> response = [];
           socket.listen(
               response.addAll,
               onDone: () {
@@ skipping 24 matching lines @@
         (HttpRequest request) {
           Expect.isNull(request.headers.value('content-length'));
           Expect.equals(-1, request.contentLength);
           request.listen((_) {}, onDone: () {
             var response = request.response;
             Expect.equals("1.0", request.protocolVersion);
             response.write("Z");
             response.close();
           });
         },
-        onError: (e) => Expect.fail("Unexpected error $e"));
+        onError: (e) {
+          String msg = "Unexpected error $e";
+          var trace = getAttachedStackTrace(e);
+          if (trace != null) msg += "\nStackTrace: $trace";
+          Expect.fail(msg);
+        });
 
     int count = 0;
     makeRequest() {
       Socket.connect("127.0.0.1", server.port).then((socket) {
         socket.write("GET / HTTP/1.0\r\n");
         socket.write("Connection: Keep-Alive\r\n\r\n");
 
         List<int> response = [];
         socket.listen(
             response.addAll,
@@ skipping 26 matching lines @@
     server.listen(
         (HttpRequest request) {
           Expect.isNull(request.headers.value('content-length'));
           Expect.equals(-1, request.contentLength);
           var response = request.response;
           response.contentLength = 1;
           Expect.equals("1.0", request.protocolVersion);
           response.write("Z");
           response.close();
         },
-        onError: (e) => Expect.fail("Unexpected error $e"));
+        onError: (e) {
+          String msg = "Unexpected error $e";
+          var trace = getAttachedStackTrace(e);
+          if (trace != null) msg += "\nStackTrace: $trace";
+          Expect.fail(msg);
+        });
 
     Socket.connect("127.0.0.1", server.port).then((socket) {
       void sendRequest() {
         socket.write("GET / HTTP/1.0\r\n");
         socket.write("Connection: Keep-Alive\r\n\r\n");
       }
 
       List<int> response = [];
       int count = 0;
       socket.listen(
@@ skipping 29 matching lines @@
   HttpServer.bind().then((server) {
     server.listen(
         (HttpRequest request) {
           Expect.isNull(request.headers.value('content-length'));
           Expect.equals(-1, request.contentLength);
           var response = request.response;
           Expect.equals("1.0", request.protocolVersion);
           response.write("Z");
           response.close();
         },
-        onError: (e) => Expect.fail("Unexpected error $e"));
+        onError: (e) {
+          String msg = "Unexpected error $e";
+          var trace = getAttachedStackTrace(e);
+          if (trace != null) msg += "\nStackTrace: $trace";
+          Expect.fail(msg);
+        });
 
     int count = 0;
     makeRequest() {
       Socket.connect("127.0.0.1", server.port).then((socket) {
         socket.write("GET / HTTP/1.0\r\n");
         socket.write("Connection: Keep-Alive\r\n\r\n");
 
         List<int> response = [];
         socket.listen(
             response.addAll,
@@ skipping 16 matching lines @@
   });
 }
 
 
 void main() {
   testHttp10NoKeepAlive();
   testHttp10ServerClose();
   testHttp10KeepAlive();
   testHttp10KeepAliveServerCloses();
 }