Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/TableColElement.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 HTMLTableColElement
-interface TableColElement extends Element default _Elements {
-
-  TableColElement();
-
-  /** @domName HTMLTableColElement.align */
-  String align;
-
-  /** @domName HTMLTableColElement.ch */
-  String ch;
-
-  /** @domName HTMLTableColElement.chOff */
-  String chOff;
-
-  /** @domName HTMLTableColElement.span */
-  int span;
-
-  /** @domName HTMLTableColElement.vAlign */
-  String vAlign;
-
-  /** @domName HTMLTableColElement.width */
-  String width;
-}