Otherwise we'll end up trying to access the out of date state later.
Fixes the following test failure backtrace:
#0 _g_log_abort ()
#1 g_logv ()
#2 g_log ()
#3 meta_monitor_manager_get_logical_monitor_from_number ()
#4 meta_window_get_work_area_for_monitor ()
#5 meta_window_get_tile_area ()
#6 constrain_maximization ()
#7 do_all_constraints ()
#8 meta_window_constrain ()
#9 meta_window_move_resize_internal ()
#10 meta_window_tile ()
https://gitlab.gnome.org/GNOME/mutter/merge_requests/912
ff799a1abe