Remove generated directories with 100s of files.

client/dom/generated/src/frog/Storage.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.
-
-class _StorageJs extends _DOMTypeJs implements Storage native "*Storage" {
-
-  final int length;
-
-  void clear() native;
-
-  String getItem(String key) native;
-
-  String key(int index) native;
-
-  void removeItem(String key) native;
-
-  void setItem(String key, String data) native;
-
-
-  // Storage needs a special implementation of dartObjectLocalStorage since it
-  // captures what would normally be an expando and places property in the
-  // storage, stringifying the assigned value.
-
-  get dartObjectLocalStorage() native """
-    if (this === window.localStorage)
-      return window._dartLocalStorageLocalStorage;
-    else if (this === window.sessionStorage)
-      return window._dartSessionStorageLocalStorage;
-    else
-      throw new UnsupportedOperationException('Cannot dartObjectLocalStorage for unknown Storage object.');
-""" { throw new UnsupportedOperationException(''); }
-
-  void set dartObjectLocalStorage(var value) native """
-    if (this === window.localStorage)
-      window._dartLocalStorageLocalStorage = value;
-    else if (this === window.sessionStorage)
-      window._dartSessionStorageLocalStorage = value;
-    else
-      throw new UnsupportedOperationException('Cannot dartObjectLocalStorage for unknown Storage object.');
-""" { throw new UnsupportedOperationException(''); }
-}