Remove lib/dom directory!

lib/dom/templates/html/dart2js/factoryprovider_MutationObserver.darttemplate

Index: lib/dom/templates/html/dart2js/factoryprovider_MutationObserver.darttemplate
===================================================================
--- lib/dom/templates/html/dart2js/factoryprovider_MutationObserver.darttemplate	(revision 12066)
+++ lib/dom/templates/html/dart2js/factoryprovider_MutationObserver.darttemplate	(working copy)
@@ -1,12 +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 $FACTORYPROVIDER {
-  factory $CONSTRUCTOR(MutationCallback callback) native '''
-    var constructor =
-        window.MutationObserver || window.WebKitMutationObserver ||
-        window.MozMutationObserver;
-    return new constructor(callback);
-  ''';
-}