[swFormExtraPlugin] fix 'required' option issue when updated afterward
[swFormExtraPlugin] fix 'required' option issue when updated afterward

git-svn-id: b6c44de1e7b159d5df0c8b18874c0a580f533a8e@21789 ee427ae8-e902-0410-961c-c3ed070cd9f9

Symfony-Plugins/swFormExtraPlugin,Symfony-Plugins/swFormExtraPlugin