When updating the dash, we already avoid all animations while the
overview is hidden. However, as we are using Main.queueDeferredWork(),
updates may be deferred up to ~20 seconds while the overview is hidden.
If the overview is entered before a queued update has taken place, it
will be run immediately on map - as the overview is visible by then,
this means animating any outstanding changes.
Work around this by skipping animations during overview transitions as
well.
https://bugzilla.gnome.org/show_bug.cgi?id=686530
f4cc2474bd