Remove generated directories with 100s of files.

client/dom/generated/src/interface/TextTrack.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 TextTrack {
-
-  static final int DISABLED = 0;
-
-  static final int HIDDEN = 1;
-
-  static final int SHOWING = 2;
-
-  final TextTrackCueList activeCues;
-
-  final TextTrackCueList cues;
-
-  final String kind;
-
-  final String label;
-
-  final String language;
-
-  int mode;
-
-  EventListener oncuechange;
-
-  void addCue(TextTrackCue cue);
-
-  void addEventListener(String type, EventListener listener, [bool useCapture]);
-
-  bool dispatchEvent(Event evt);
-
-  void removeCue(TextTrackCue cue);
-
-  void removeEventListener(String type, EventListener listener, [bool useCapture]);
-}