Modify apidoc to prefer handwritten HTML5 docs over those in MDN or generated code.

lib/html/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.
 
-/// @domName AbstractWorker
+/// An HTML5 Abstract Worker.
 interface AbstractWorker extends EventTarget {
 
   /**
-   * @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent
+   * 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]);
 }
 
 interface AbstractWorkerEvents extends Events {
 
   EventListenerList get error();
 }