Revert "Make sure we properly account for transitive liveness when processing bridge objects. Fixes #13858"

This reverts commit 7d6daf79af574805f8bd3a4be59b1abde316f129.

The fix for #13858 introduced Bug #14999:

	https://bugzilla.xamarin.com/show_bug.cgi?id=14999

It basically replaces a consistent GC-related crash with an entirely
random GC crash (fun!), stalling QA.

Revert the #13858 fix so that QA can continue, testing the
Microsoft Remediation Patches.