Remove the old hand-written HTML doc format, which has not worked for months.

tools/dom/doc/interface/AbstractWorker.dartdoc

-// 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.
-
-// WARNING:
-//   This file contains documentation that is merged into the real source.
-//   Do not make code changes here.
-
-/// An HTML5 Abstract Worker.
-abstract class AbstractWorker implements EventTarget {
-
-  /**
-   * The valid events associated with an AbstractWorker.
-   */
-  AbstractWorkerEvents get on;
-
-  /** @domName AbstractWorker.addEventListener */
-  void $dom_addEventListener(String type, EventListener listener, [bool useCapture]);
-
-  /** @domName AbstractWorker.dispatchEvent */
-  bool $dom_dispatchEvent(Event evt);
-
-  /** @domName AbstractWorker.removeEventListener */
-  void $dom_removeEventListener(String type, EventListener listener, [bool useCapture]);
-}
-
-abstract class AbstractWorkerEvents implements Events {
-
-  EventListenerList get error;
-}