Remove AsyncError with Expando.

pkg/webdriver/lib/webdriver.dart

 // Copyright (c) 2011, 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.
 
 library webdriver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:uri';
@@ skipping 197 matching lines @@
     }
   }
 
   WebDriverBase([
       this._host = 'localhost',
       this._port = 4444,
       this._path = '/wd/hub']) {
     _url = 'http://$_host:$_port$_path';
   }
 
-  void _failRequest(Completer completer, error, StackTrace stackTrace) {
+  void _failRequest(Completer completer, error, [stackTrace]) {
     if (completer != null) {
-      completer.completeError(new WebDriverError(-1, error), stackTrace);
+      var trace = stackTrace != null ? stackTrace, getAttachedStackTrace(error);
+      completer.completeError(new WebDriverError(-1, error), trace);
     }
   }
 
   /**
    * Execute a request to the WebDriver server. [http_method] should be
    * one of 'GET', 'POST', or 'DELETE'. [command] is the text to append
    * to the base URL path to get the full URL. [params] are the additional
    * parameters. If a [List] or [Map] they will be posted as JSON parameters.
    * If a number or string, "/params" is appended to the URL.
    */
@@ skipping 35 matching lines @@
             var value = null;
             // For some reason we get a bunch of NULs on the end
             // of the text and the json.parse blows up on these, so
             // strip them with trim().
             // These NULs can be seen in the TCP packet, so it is not
             // an issue with character encoding; it seems to be a bug
             // in WebDriver stack.
             results = new String.fromCharCodes(body).trim();
             if (!successCodes.contains(rsp.statusCode)) {
               _failRequest(completer, 
-                  'Unexpected response ${rsp.statusCode}; $results', null);
+                  'Unexpected response ${rsp.statusCode}; $results');
               completer = null;
               return;
             }
             if (status == 0 && results.length > 0) {
               // 4xx responses send plain text; others send JSON.
               if (rsp.statusCode < 400) {
                 results = json.parse(results);
                 status = results['status'];
               }
               if (results is Map && (results as Map).containsKey('value')) {
                 value = results['value'];
               }
               if (value is Map && value.containsKey('message')) {
                 message = value['message'];
               }
             }
             if (status == 0) {
               if (customHandler != null) {
                 customHandler(rsp, value);
               } else if (completer != null) {
                 completer.complete(value);
               }
             }
-          }, onError: (e) {
-            _failRequest(completer, e.error, e.stackTrace);
+          }, onError: (error) {
+            _failRequest(completer, error);
             completer = null;
           });
         })
-        .catchError((e) {
-          _failRequest(completer, e.error, e.stackTrace);
+        .catchError((error) {
+          _failRequest(completer, error);
           completer = null;
         });
       })
-      .catchError((e) {
-        _failRequest(completer, e.error, e.stackTrace);
+      .catchError((error) {
+        _failRequest(completer, error);
         completer = null;
       });
     } catch (e, s) {
       _failRequest(completer, e, s);
       completer = null;
     }
   }
 
   Future _get(String extraPath,
       [Completer completer, Function customHandler]) {
@@ skipping 1119 matching lines @@
    *
    * 'timestamp' (int) - The timestamp of the entry.
    * 'level' (String) - The log level of the entry, for example, "INFO".
    * 'message' (String) - The log message.
    *
    * This works with Firefox but Chrome returns a 500 response due to a 
    * bad cast.
    */
   Future<List<Map>> getLogs(String type) => _post('log', { 'type': type });
 }