Remove generated directories with 100s of files.

client/dom/generated/src/wrapping/_CanvasGradientWrappingImplementation.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 _CanvasGradientWrappingImplementation extends DOMWrapperBase implements CanvasGradient {
-  _CanvasGradientWrappingImplementation() : super() {}
-
-  static create__CanvasGradientWrappingImplementation() native {
-    return new _CanvasGradientWrappingImplementation();
-  }
-
-  void addColorStop(num offset, String color) {
-    _addColorStop(this, offset, color);
-    return;
-  }
-  static void _addColorStop(receiver, offset, color) native;
-
-  String get typeName() { return "CanvasGradient"; }
-}