Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_WebGLLoseContextWrappingImplementation.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 _WebGLLoseContextWrappingImplementation extends DOMWrapperBase implements WebGLLoseContext {
-  _WebGLLoseContextWrappingImplementation() : super() {}
-
-  static create__WebGLLoseContextWrappingImplementation() native {
-    return new _WebGLLoseContextWrappingImplementation();
-  }
-
-  void loseContext() {
-    _loseContext(this);
-    return;
-  }
-  static void _loseContext(receiver) native;
-
-  void restoreContext() {
-    _restoreContext(this);
-    return;
-  }
-  static void _restoreContext(receiver) native;
-
-  String get typeName() { return "WebGLLoseContext"; }
-}