Tor Launcher's custom bridge field only allows one line of input

In the ESR68-based Tor Browser, Tor Launcher's custom bridge input field only allows one line of input. Some detective work reveals that Mozilla was in the process of removing XUL textbox during the ESR68 cycle and now it has been completely removed (for Firefox 71): https://bugzilla.mozilla.org/show_bug.cgi?id=1513325

They have switched everything to use html:input and html:textarea and we will need to do the same, eventually. Prior to ESR68, they removed support for multiline textbox elements, which is the cause of the custom bridge field breakage.

We are working on a fix, although I guess it is too late for Tor Browser 9.0? I wish we would have noticed this sooner.