IC system does its best to properly mark stable transition source maps
as unstable (see https://chromium-review.googlesource.com/483442)
however an already recorded map can be deprecated later and the
optimizing compiler may try to generate an elements kind transition
from the updated version of deprecated map which can "become" stable
again.

Bug: chromium:723455
Change-Id: Ic0c392f153587c3cd7c7623a3a6ea85ec72ad5bd
Reviewed-on: https://chromium-review.googlesource.com/507887
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45384}