Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_DataTransferItemWrappingImplementation.dart

-// Copyright (c) 2011, 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.
-
-class _DataTransferItemWrappingImplementation extends DOMWrapperBase implements DataTransferItem {
-  _DataTransferItemWrappingImplementation() : super() {}
-
-  static create__DataTransferItemWrappingImplementation() native {
-    return new _DataTransferItemWrappingImplementation();
-  }
-
-  String get kind() { return _get_kind(this); }
-  static String _get_kind(var _this) native;
-
-  String get type() { return _get_type(this); }
-  static String _get_type(var _this) native;
-
-  Blob getAsFile() {
-    return _getAsFile(this);
-  }
-  static Blob _getAsFile(receiver) native;
-
-  void getAsString([StringCallback callback = null]) {
-    _getAsString(this, callback);
-    return;
-  }
-  static void _getAsString(receiver, callback) native;
-
-  String get typeName() { return "DataTransferItem"; }
-}