It seems inconsistent whether this does a form submit, which was at the heart of why I had to do such a big reworking of the forms system - as I couldn't rely on it doing submission, or NOT doing submission. For some combination of inconsistency across browsers and change/disagreement of whether this represents some kind of security risk (opaque artificial submission of forms rather than using a direct documented mechanism).
Maybe we will just have to no longer have this, and rely on form.submit();