This reverts commit 7a5a777c.

Reason for revert: crashing in test-api

Original change's description:
> [heap] Add mechanism for tracking invalidated slots per memory chunk.
> 
> For correct slots recording in concurrent marker, we need to resolve
> the race that happens when
> 1) the mutator is invalidating slots for double unboxing or string
> conversions
> 2) and the concurrent marker is recording these slots.
> 
> This patch adds a data-structure for tracking the invalidated objects.
> Thus we can allow the concurrent marker to record slots without
> worrying about clearing them. During old-to-old pointer updating phase
> we re-check all slots that belong to the invalidated objects.
> 
> BUG=chromium:694255
> 
> Change-Id: Ifc3d82918cd3b96e5a5fb7125691626a56f4ab83
> Reviewed-on: https://chromium-review.googlesource.com/591810
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47049}

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

Change-Id: I7f4f8e8cb027b921a82e9c0a0623536af02581fb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:694255
Reviewed-on: https://chromium-review.googlesource.com/595994Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47052}