webshims group-required test not firing on checkValidity

webshims group-required test not firing on checkValidity

I've got a handlebars template that has a group of checkboxes named the same thing and decorated with the "group-required" class. The validity check properly fails on focusout (for example when tabbing through the form and leaving all of those elements unchecked, but when I call checkValidity() on the form element in javascript with none of those values checked, the forms validity check passes. On the same form, text inputs marked required are marked as invalid if empty when calling checkValidity()

On a test page with a similar grouping of checkboxes, firing checkValidity() on the form marks the checkboxes invalid if none are checked.

An abbreviated version of the form output of the handlebars template is available at  https://gist.github.com/4594041.