Browser inconsistencies wrt data validity semantics on form elements

Premise: If the :invalid and :valid selectors apply on a form element, than
that element has data validity semantics.

I've tested in a few desktop browsers (on Windows) and I've noticed some
inconsistencies: The <form> element does not have data validity semantics
in Chrome/IE11 but it has in Firefox. The behavior is opposite wrt <input
type=submit> (Semantics in chrome/IE11 but not in Firefox).

Live demo: http://jsfiddle.net/RxLzM/4/

>From what I can see in the HTML 5.1 spec, there seem to be no validity
requirements for <input type=submit>, and I'm not sure about <form>.