Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_MetadataWrappingImplementation.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 _MetadataWrappingImplementation extends DOMWrapperBase implements Metadata {
-  _MetadataWrappingImplementation() : super() {}
-
-  static create__MetadataWrappingImplementation() native {
-    return new _MetadataWrappingImplementation();
-  }
-
-  Date get modificationTime() { return _get_modificationTime(this); }
-  static Date _get_modificationTime(var _this) native;
-
-  int get size() { return _get_size(this); }
-  static int _get_size(var _this) native;
-
-  String get typeName() { return "Metadata"; }
-}