Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/Notation.dartdoc

Index: lib/html/doc/interface/Notation.dartdoc
diff --git a/lib/html/doc/interface/Notation.dartdoc b/lib/html/doc/interface/Notation.dartdoc
deleted file mode 100644
index 5fcf66fd5695b4d378c288971dfc34738468fb6c..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/Notation.dartdoc
+++ /dev/null
@@ -1,17 +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 Notation
-interface Notation extends Node {
-
-  /** @domName Notation.publicId */
-  final String publicId;
-
-  /** @domName Notation.systemId */
-  final String systemId;
-}