This reverts commit 68a8bdd8.

Reason for revert: memory regression: crbug.com/921239

Original change's description:
> [heap] Remove bailout marking worklist.
> 
> The concurrent marker can now process all objects.
> This patch also eagerly visits the objects that undergo layout
> changes. This is because previously such objects were pushed
> onto the bailout worklist, which is gone now.
> To preserve the incremental step accounting, the patch introduces
> a new GC tracer scope called MC_INCREMENTAL_LAYOUT_CHANGE.
> 
> Bug: v8:8486
> Change-Id: Ic1c2f0d4e2ac0602fc945f3258af9624247bd65f
> Reviewed-on: https://chromium-review.googlesource.com/c/1386486
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#58712}

TBR=ulan@chromium.org,mlippautz@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:8486, chromium:921239
Change-Id: I1f851b948f4ce403316e469999f0b16e8dfdb62d
Reviewed-on: https://chromium-review.googlesource.com/c/1408990
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58787}