Remove generic typedefs that dart2js chokes on.

dart/sdk/lib/core/list.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.core;
 
 /**
  * A [List] is an indexable collection with a length. It can be of
  * fixed size or extendable.
  */
@@ skipping 349 matching lines @@
     _position = _list.length;
     _current = null;
     return false;
   }
 
   E get current => _current;
 }
 
 class MappedList<S, T> extends NonExtensibleListMixin<T> {
   final List<S> _list;
-  final _Transformation<S, T> _f;
+  // TODO(ahe): Restore type when feature is implemented in dart2js
+  // checked mode.
+  final /* _Transformation<S, T> */ _f;
 
   MappedList(this._list, T this._f(S element));
 
   T operator[](int index) => _f(_list[index]);
   int get length => _list.length;
 }
 
 /**
  * An immutable view of a [List].
  */
@@ skipping 43 matching lines @@
 
   ListView<E> take(int takeCount) {
     if (takeCount is! int || takeCount < 0) {
       throw new ArgumentError(takeCount);
     }
     int newLength = takeCount;
     if (_length != null && takeCount > _length) newLength = _length;
     return new ListView(_list, _offset, newLength);
   }
 }