Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_CSSImportRuleWrappingImplementation.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 _CSSImportRuleWrappingImplementation extends _CSSRuleWrappingImplementation implements CSSImportRule {
-  _CSSImportRuleWrappingImplementation() : super() {}
-
-  static create__CSSImportRuleWrappingImplementation() native {
-    return new _CSSImportRuleWrappingImplementation();
-  }
-
-  String get href() { return _get_href(this); }
-  static String _get_href(var _this) native;
-
-  MediaList get media() { return _get_media(this); }
-  static MediaList _get_media(var _this) native;
-
-  CSSStyleSheet get styleSheet() { return _get_styleSheet(this); }
-  static CSSStyleSheet _get_styleSheet(var _this) native;
-
-  String get typeName() { return "CSSImportRule"; }
-}