If an actor has not been painted yet, or it's not going to be painted,
we can ignore transitions queued on it.

By ignoring transitions on actors that have not been painted yet, we can
avoid doing work during the set up phase of the scene graph, as well as
avoiding actors "flying in" from nowhere.

Obviously, we have to take into account potential clones, so we need to
check that the actor is not part of a cloned branch of the scene graph,
as well as checking if the actor has mapped clones.