Remove AsyncError with Expando.

tests/lib/async/event_helper.dart

 // Copyright (c) 2012, 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 event_helper;
 
 import 'dart:async';
 
 abstract class Event {
   void replay(EventSink sink);
@@ skipping 11 matching lines @@
   bool operator==(Object other) {
     if (other is! DataEvent) return false;
     DataEvent otherEvent = other;
     return data == other.data;
   }
 
   String toString() => "DataEvent: $data";
 }
 
 class ErrorEvent implements Event {
-  final AsyncError error;
+  final error;
 
   ErrorEvent(this.error);
 
   void replay(EventSink sink) { sink.addError(error); }
 
   int get hashCode => error.error.hashCode;
 
   bool operator==(Object other) {
     if (other is! ErrorEvent) return false;
     ErrorEvent otherEvent = other;
-    return error.error == other.error.error;
+    return error == other.error;
   }
 
-  String toString() => "ErrorEvent: ${error.error}";
+  String toString() => "ErrorEvent: ${error}";
 }
 
 class DoneEvent implements Event {
   const DoneEvent();
 
   void replay(EventSink sink) { sink.close(); }
 
   int get hashCode => 42;
 
   bool operator==(Object other) => other is DoneEvent;
@@ skipping 13 matching lines @@
 
   /** Capture events from a stream into a new [Events] object. */
   factory Events.capture(Stream stream,
                          { bool cancelOnError: false }) = CaptureEvents;
 
   // EventSink interface.
   void add(var value) {
     events.add(new DataEvent(value));
   }
 
-  void addError(AsyncError error) {
+  void addError(error) {
     events.add(new ErrorEvent(error));
   }
 
   void close() {
     events.add(const DoneEvent());
   }
 
   // Error helper for creating errors manually..
-  void error(var value) { addError(new AsyncError(value, null)); }
+  void error(var value) { addError(value); }
 
   /** Replay the captured events on a sink. */
   void replay(EventSink sink) {
     for (int i = 0; i < events.length; i++) {
       events[i].replay(sink);
     }
   }
 
   /**
    * Create a new [Events] with the same captured events.
@@ skipping 39 matching lines @@
   CaptureEvents(Stream stream,
                 { bool cancelOnError: false })
       : onDoneSignal = new Completer() {
     this.cancelOnError = cancelOnError;
     subscription = stream.listen(add,
                                  onError: addError,
                                  onDone: close,
                                  cancelOnError: cancelOnError);
   }
 
-  void addError(AsyncError error) {
+  void addError(error) {
     super.addError(error);
     if (cancelOnError) onDoneSignal.complete(null);
   }
 
   void close() {
     super.close();
     if (onDoneSignal != null) onDoneSignal.complete(null);
   }
 
   void pause([Future resumeSignal]) {
     subscription.pause(resumeSignal);
   }
 
   void resume() {
     subscription.resume();
   }
 
   void onDone(void action()) {
     onDoneSignal.future.whenComplete(action);
   }
 }