Remove AsyncError with Expando.

tools/dom/src/EventStreamProvider.dart

Index: tools/dom/src/EventStreamProvider.dart
diff --git a/tools/dom/src/EventStreamProvider.dart b/tools/dom/src/EventStreamProvider.dart
index 84febfe28e9bdbed27914e803f08aefadfec5069..1e3b258dc711819ef9954ff4178a520765f3024d 100644
--- a/tools/dom/src/EventStreamProvider.dart
+++ b/tools/dom/src/EventStreamProvider.dart
@@ -19,9 +19,9 @@ class _EventStream<T extends Event> extends Stream<T> {
   bool get isBroadcast => true;
 
   StreamSubscription<T> listen(void onData(T event),
-      { void onError(AsyncError error),
-      void onDone(),
-      bool unsubscribeOnError}) {
+      { void onError(error),
+        void onDone(),
+        bool unsubscribeOnError}) {
 
     return new _EventStreamSubscription<T>(
         this._target, this._eventType, onData, this._useCapture);
@@ -63,7 +63,7 @@ class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
   }
 
   /// Has no effect.
-  void onError(void handleError(AsyncError error)) {}
+  void onError(void handleError(error)) {}
 
   /// Has no effect.
   void onDone(void handleDone()) {}