Reapply DOMFormData => FormData rename. (this time with a fix for Dartium)

lib/html/doc/interface/FormData.dartdoc

Index: lib/html/doc/interface/FormData.dartdoc
===================================================================
--- lib/html/doc/interface/FormData.dartdoc	(revision 0)
+++ lib/html/doc/interface/FormData.dartdoc	(revision 0)
@@ -0,0 +1,14 @@
+// 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 DOMFormData
+interface FormData {
+
+  /** @domName DOMFormData.append */
+  void append(String name, String value, String filename);
+}