Restore focus correctly when closing a fullscreen view

We weren't calling seat_send_focus. I think this was previously called
by seat_set_focus_warp.

sway/input/seat.c

@@ -168,12 +168,9 @@ static void handle_seat_node_destroy(struct wl_listener *listener, void *data) {
 
 		// the structure change might have caused it to move up to the top of
 		// the focus stack without sending focus notifications to the view
-		if (seat_get_focus(seat) == next_focus) {
 		seat_send_focus(next_focus, seat);
-		} else {
 		seat_set_focus(seat, next_focus);
 	}
-	}
 }
 
 static struct sway_seat_node *seat_node_from_node(