If selection_name is not passed to this script, try to get it using "listbox_list_selection_name" at the request.

This is required to ListBoxes (showed from a website using erp5_web) use A..Z button for reset the selection, In this casethe selection_name does not come with the request when this button is clicked.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34078 20353a03-c40f-0410-a6d1-a30d3c3de9de