Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/DedicatedWorkerContext.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 DedicatedWorkerContext
-interface DedicatedWorkerContext extends WorkerContext {
-
-  /**
-   * @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent
-   */
-  DedicatedWorkerContextEvents get on();
-
-  /** @domName DedicatedWorkerContext.postMessage */
-  void postMessage(Object message, [List messagePorts]);
-
-  /** @domName DedicatedWorkerContext.webkitPostMessage */
-  void webkitPostMessage(Object message, [List transferList]);
-}
-
-interface DedicatedWorkerContextEvents extends WorkerContextEvents {
-
-  EventListenerList get message();
-}