Blender Git Loki

Fix T57070: Take Two of 2.8 Crash in sculpting mode with tilling and Dyntopo.

Accessing ob->bb directly is not a good idea anyway.

Still, would like to know why/where this bbox is freed, since it is
allocated at least once by depsgraph eval, as part of
`BKE_object_handle_data_update()` function...