Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/BodyElement.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 HTMLBodyElement
-interface BodyElement extends Element default _Elements {
-
-  BodyElement();
-
-  /**
-   * @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent
-   */
-  BodyElementEvents get on();
-
-  /** @domName HTMLBodyElement.aLink */
-  String aLink;
-
-  /** @domName HTMLBodyElement.background */
-  String background;
-
-  /** @domName HTMLBodyElement.bgColor */
-  String bgColor;
-
-  /** @domName HTMLBodyElement.link */
-  String link;
-
-  /** @domName HTMLBodyElement.vLink */
-  String vLink;
-}
-
-interface BodyElementEvents extends ElementEvents {
-
-  EventListenerList get beforeUnload();
-
-  EventListenerList get blur();
-
-  EventListenerList get error();
-
-  EventListenerList get focus();
-
-  EventListenerList get hashChange();
-
-  EventListenerList get load();
-
-  EventListenerList get message();
-
-  EventListenerList get offline();
-
-  EventListenerList get online();
-
-  EventListenerList get popState();
-
-  EventListenerList get resize();
-
-  EventListenerList get storage();
-
-  EventListenerList get unload();
-}