Remove generated directories with 100s of files.

client/dom/generated/src/frog/HTMLIFrameElement.dart

-// Copyright (c) 2012, 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.
-
-class _HTMLIFrameElementJs extends _HTMLElementJs implements HTMLIFrameElement native "*HTMLIFrameElement" {
-
-  String align;
-
-  String frameBorder;
-
-  String height;
-
-  String longDesc;
-
-  String marginHeight;
-
-  String marginWidth;
-
-  String name;
-
-  String sandbox;
-
-  String scrolling;
-
-  String src;
-
-  String width;
-
-  _SVGDocumentJs getSVGDocument() native;
-
-
-  Window get _contentWindow() native "return this.contentWindow;";
-
-  // Override contentWindow to return secure wrapper.
-  Window get contentWindow() {
-    return _DOMWindowCrossFrameImpl._createSafe(_contentWindow);
-  }
-}