Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/ElementTimeControl.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 ElementTimeControl
-interface ElementTimeControl {
-
-  /** @domName ElementTimeControl.beginElement */
-  void beginElement();
-
-  /** @domName ElementTimeControl.beginElementAt */
-  void beginElementAt(num offset);
-
-  /** @domName ElementTimeControl.endElement */
-  void endElement();
-
-  /** @domName ElementTimeControl.endElementAt */
-  void endElementAt(num offset);
-}