qunit/testrunner: Log relevant node in unfinished animations and reset

Having unfinished animations affect other test can be a problem,
but when it does happen, having just a number isn't helpful in
trying to pinpoint the cause.

Logging a description of the element should make this relatively
straight forward.

Also reset the animations after the test so that the next test has a
clean start (instead of the current situation where every subsequent
test, until the animation finishes, also reports it as a failure).

Example:

 Unfinished animation #0 in fx queue on <div class="mw-notification
  mw-notification-tag-legacy" style="opacity: 0; "/>

Change-Id: I41058c4cba3383e3ad1456990ccf8dae4ca64951
mediawiki.util: Remove test for jsMessage

jsMessage uses mw.notify, which involves an animation.

mw.notify yields an mw.Notification object which has a reference
to the relevant elements.

However the deprecated jsMessage wrapper only returns boolean, so
we have no link to the element and no way to wait for the
animation to finish.

We could set up a mock clock in the test to skip the animation.
However, in this case the test was already useless as method
isn't testable (hardcoded booolean return).

This test was causing the QUnit test suite to fail occasionally
as the mw.notify animation was unfinished and would leak into
other tests.

Change-Id: Iffa91a3969bf69264b585e27ca44f85883ae2892