These used to be used for the list of newly freed objects, but that's
no longer a thing.

Change-Id: I5a4503137b74ec0eae5372ca271b1aa0b32df074
Reviewed-on: https://go-review.googlesource.com/22557Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>