Use typedefs in lib.

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;
 
 /** Abstract and private interface for a place to put events. */
 abstract class _EventSink<T> {
   void _add(T data);
   void _addError(Object error);
@@ skipping 59 matching lines @@
    * Set by calling [cancel], or by handling a "done" event, or an "error" event
    * when `cancelOnError` is true.
    */
   static const int _STATE_CANCELED = 8;
   static const int _STATE_IN_CALLBACK = 16;
   static const int _STATE_HAS_PENDING = 32;
   static const int _STATE_PAUSE_COUNT = 64;
   static const int _STATE_PAUSE_COUNT_SHIFT = 6;
 
   /* Event handlers provided in constructor. */
-  /* TODO(7733): Fix Function->_DataHandler<T> when dart2js understands
-   * parameterized function types. */
-  Function _onData;
+  _DataHandler<T> _onData;
   _ErrorHandler _onError;
   _DoneHandler _onDone;
   final _Zone _zone = _Zone.current;
 
   /** Bit vector based on state-constants above. */
   int _state;
 
   /**
    * Queue of pending events.
    *
@@ skipping 909 matching lines @@
       _FutureImpl<bool> hasNext = _futureOrPrefetch;
       _clear();
       hasNext._setValue(false);
       return;
     }
     _subscription.pause();
     _futureOrPrefetch = null;
     _state = _STATE_EXTRA_DONE;
   }
 }