It is created, unconditionally fired only once (right after creation),
and then used only with add(), which becomes a synchronous
self-call.
I've searched in Wikimedia Git and Codesearch, and found no uses
of `logEventQueue` or `mw.uls.eventlogger` outside this file.
Change-Id: I3832bcb409fc919c2078e583d50e20413dede163