Update the lab to handle the new menu structure

[dpvc]

This PR implements the changes needed to the lab in order to handle the new menu structure in the are-menus branch of Mathjax-src.

[zorkow]

This works with the sre-menus branch. I would love to use it to test more thoroughly the combinations for PR 1058, which is a bit of a catch 22. I'll finish that PR as best as possible right now and then once everything is merged I'll tests again.

[dpvc]

The sre-menus branch is built on top of the fix/ff_safari_issues branch. Is that the problem?

[dpvc]

I've pushed another commit that fixes a problem where the lab would set both enableSpeech and enableBraille when one or the other is selected. This is why both aria labels were being generated even when only one menu selection was made or one checkbox was selected. So this new commit makes the aria-label and aria-braillelabel work correctly.

(It took me forever to find this, as I thought it was in the menu code, but it was actually in the lab. Argh!)