Remove generated directories with 100s of files.

client/dom/generated/src/interface/MediaController.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.
-
-// WARNING: Do not edit - generated code.
-
-interface MediaController default _MediaControllerFactoryProvider {
-
-  MediaController();
-
-  final TimeRanges buffered;
-
-  num currentTime;
-
-  num defaultPlaybackRate;
-
-  final num duration;
-
-  bool muted;
-
-  final bool paused;
-
-  num playbackRate;
-
-  final TimeRanges played;
-
-  final TimeRanges seekable;
-
-  num volume;
-
-  void addEventListener(String type, EventListener listener, [bool useCapture]);
-
-  bool dispatchEvent(Event evt);
-
-  void pause();
-
-  void play();
-
-  void removeEventListener(String type, EventListener listener, [bool useCapture]);
-}