R1:eecee172139e

Activate "jx-toggle-class" on click to fix broken mobile behavior

Summary:
See downstream <https://phabricator.wikimedia.org/T201480>. Searching for things on mobile is a significant challenge because clicking the "Magnifying Glass" icon shows and then immediately hides the menu. I believe some aspect of iOS event handling has changed since this was originally written.

At some point, I'd like to rewrite this to work more cleanly and get rid of `jx-toggle-class`. In particular, it isn't smart enough to…