This reverts commit 0f23cedd.

Reason for revert: buildbot failures

Original change's description:
> [in-place weak refs] Replace WeakCells in DescriptorArray.
> 
> BUG=v8:7308
> 
> Change-Id: Ib0ad52916d6f5b65e7612981b467b491d832f505
> Reviewed-on: https://chromium-review.googlesource.com/1075053
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#53473}

TBR=ulan@chromium.org,marja@chromium.org,tebbi@chromium.org,ishell@chromium.org

Change-Id: I713ab10650f933a8218a61521868d6cd16cb821e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7308
Reviewed-on: https://chromium-review.googlesource.com/1082218Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53474}