If there is already a PassStyleOfEndowmentSymbol property on the global, then presumably it was endowed for us by liveslots with a passStyleOf function, so we should use and export that one instead. Other software may have left it for us here, but it would require write access to our global, or the ability to provide endowments to our global, both of which seems adequate as a test of whether it is authorized to serve the same role as liveslots.

NOTE HAZARD: This use by liveslots does rely on passStyleOf being deterministic. If it is not, then in a liveslot-like virtualized environment, it can be used to detect GC.