Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/HTMLCollection.dartdoc

Index: lib/html/doc/interface/HTMLCollection.dartdoc
diff --git a/lib/html/doc/interface/HTMLCollection.dartdoc b/lib/html/doc/interface/HTMLCollection.dartdoc
deleted file mode 100644
index e75c74e68996e32c8b52105257d7abb1cef59ca2..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/HTMLCollection.dartdoc
+++ /dev/null
@@ -1,20 +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 HTMLCollection
-interface HTMLCollection extends List<Node> {
-
-  /** @domName HTMLCollection.length */
-  final int length;
-
-  /** @domName HTMLCollection.item */
-  Node item(int index);
-
-  /** @domName HTMLCollection.namedItem */
-  Node namedItem(String name);
-}