Bug 1047143 - close aps entering task-manager, exitToApp to open/restore

Exactly, I'll add a comment here. The idea is that while all apps are closed while the task switcher is showing, both AppWindowManager and StackManager should otherwise be in a viable state, with activeApp and position respective properties kept accurate.
Note that while in the carousel-style switcher we have a currentPosition which is the centered card, in the task strip we will lose that so I'm not attempting to update position until the task switcher is dismissed