Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_CustomEventWrappingImplementation.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 _CustomEventWrappingImplementation extends _EventWrappingImplementation implements CustomEvent {
-  _CustomEventWrappingImplementation() : super() {}
-
-  static create__CustomEventWrappingImplementation() native {
-    return new _CustomEventWrappingImplementation();
-  }
-
-  Object get detail() { return _get_detail(this); }
-  static Object _get_detail(var _this) native;
-
-  void initCustomEvent(String typeArg, bool canBubbleArg, bool cancelableArg, Object detailArg) {
-    _initCustomEvent(this, typeArg, canBubbleArg, cancelableArg, detailArg);
-    return;
-  }
-  static void _initCustomEvent(receiver, typeArg, canBubbleArg, cancelableArg, detailArg) native;
-
-  String get typeName() { return "CustomEvent"; }
-}