Remove generic typedefs that dart2js chokes on.

dart/sdk/lib/async/stream_impl.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.
 
 // part of dart.async;
 
 // States shared by single/multi stream implementations.
 
 /// Initial and default state where the stream can receive and send events.
 const int _STREAM_OPEN = 0;
@@ skipping 625 matching lines @@
  *
  * The subscription is in one of three states:
  * * Subscribed.
  * * Paused-and-subscribed.
  * * Unsubscribed.
  * Unsubscribing also unpauses.
  */
 class _StreamSubscriptionImpl<T> extends _StreamListener<T>
                                  implements StreamSubscription<T> {
   final bool _unsubscribeOnError;
-  _DataHandler<T> _onData;
+  // TODO(ahe): Restore type when feature is implemented in dart2js
+  // checked mode.
+  var /* _DataHandler<T> */ _onData;
   _ErrorHandler _onError;
   _DoneHandler _onDone;
   _StreamSubscriptionImpl(_StreamImpl source,
                           this._onData,
                           this._onError,
                           this._onDone,
                           this._unsubscribeOnError) : super(source);
 
   void onData(void handleData(T event)) {
     if (handleData == null) handleData = _nullDataHandler;
@@ skipping 351 matching lines @@
     if (_isComplete) {
       throw new StateError("Subscription has been canceled.");
     }
     if (_timer != null) {
       _timer.cancel();
       _timer = null;
     }
     _pauseCount = 0;
   }
 }