This is a reland of 4a2b2b2e

Original change's description:
> [Heap]: Marking use Jobs.
> 
> StopRequest is removed in favor of:
> COMPLETE_TASKS_FOR_TESTING -> JoinForTesting()
> PREEMPT_TASKS -> Pause()
> COMPLETE_ONGOING_TASKS now has the same behavior as PREEMPT_TASKS
> - we should avoid waiting on the main thread as much as possible.
> 
> Change-Id: Icceeb4f0c0fda2ed234b2f26fe308b11410fcfb7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2376166
> Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70037}

Change-Id: I386f619501ad07997278543868bc889a60afcc8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2423938
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70387}