Remove generated directories with 100s of files.

client/dom/generated/src/interface/EventSource.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 EventSource extends EventTarget default _EventSourceFactoryProvider {
-
-  EventSource(String scriptUrl);
-
-  static final int CLOSED = 2;
-
-  static final int CONNECTING = 0;
-
-  static final int OPEN = 1;
-
-  final String URL;
-
-  final int readyState;
-
-  final String url;
-
-  void addEventListener(String type, EventListener listener, [bool useCapture]);
-
-  void close();
-
-  bool dispatchEvent(Event evt);
-
-  void removeEventListener(String type, EventListener listener, [bool useCapture]);
-}