Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/Touch.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 Touch
-interface Touch {
-
-  /** @domName Touch.clientX */
-  final int clientX;
-
-  /** @domName Touch.clientY */
-  final int clientY;
-
-  /** @domName Touch.identifier */
-  final int identifier;
-
-  /** @domName Touch.pageX */
-  final int pageX;
-
-  /** @domName Touch.pageY */
-  final int pageY;
-
-  /** @domName Touch.screenX */
-  final int screenX;
-
-  /** @domName Touch.screenY */
-  final int screenY;
-
-  /** @domName Touch.target */
-  final EventTarget target;
-
-  /** @domName Touch.webkitForce */
-  final num webkitForce;
-
-  /** @domName Touch.webkitRadiusX */
-  final int webkitRadiusX;
-
-  /** @domName Touch.webkitRadiusY */
-  final int webkitRadiusY;
-
-  /** @domName Touch.webkitRotationAngle */
-  final num webkitRotationAngle;
-}