With this change we support allocation of objects and keeping them
alive via conservative stack scan.

This reverts commit 2b047a58.

Change-Id: Iac1913e7ef0556c28399509a160777a89e60150c
Bug: chromium:1056170
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2137402
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67016}