Remove explicit interface versions of dartdoc files.

lib/html/doc/nodoc-src/_XMLHttpRequestFactoryProvider.dart

Index: lib/html/doc/nodoc-src/_XMLHttpRequestFactoryProvider.dart
diff --git a/lib/html/doc/nodoc-src/_XMLHttpRequestFactoryProvider.dart b/lib/html/doc/nodoc-src/_XMLHttpRequestFactoryProvider.dart
deleted file mode 100644
index 6e47cb46801aa5f49d2f7746ac760d2399c1f5fb..0000000000000000000000000000000000000000
--- a/lib/html/doc/nodoc-src/_XMLHttpRequestFactoryProvider.dart
+++ /dev/null
@@ -1,10 +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.
-
-class _XMLHttpRequestFactoryProvider {
-  factory HttpRequest() => null;
-
-  factory HttpRequest.get(String url, onSuccess(HttpRequest request)) =>
-      null;
-}