Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/LabelElement.dartdoc

Index: lib/html/doc/interface/LabelElement.dartdoc
diff --git a/lib/html/doc/interface/LabelElement.dartdoc b/lib/html/doc/interface/LabelElement.dartdoc
deleted file mode 100644
index f173655cf44a318988a915dec314e31453632017..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/LabelElement.dartdoc
+++ /dev/null
@@ -1,22 +0,0 @@
-// 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 HTMLLabelElement
-interface LabelElement extends Element default _Elements {
-
-  LabelElement();
-
-  /** @domName HTMLLabelElement.control */
-  final Element control;
-
-  /** @domName HTMLLabelElement.form */
-  final FormElement form;
-
-  /** @domName HTMLLabelElement.htmlFor */
-  String htmlFor;
-}