Revert "Add some sweet XML classes."

client/html/src/XMLDocument.dart

Index: client/html/src/XMLDocument.dart
diff --git a/client/html/src/XMLDocument.dart b/client/html/src/XMLDocument.dart
deleted file mode 100644
index 47fc63a54eff9d728aad59e96d81b69d96c593fa..0000000000000000000000000000000000000000
--- a/client/html/src/XMLDocument.dart
+++ /dev/null
@@ -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.
-
-interface XMLDocument extends Document, XMLElement
-    default XMLDocumentWrappingImplementation {
-
-  /** WARNING: Currently this doesn't work on Dartium (issue 649). */
-  XMLDocument.xml(String xml);
-
-  XMLDocument clone(bool deep);
-}