Revert of [heap] Concurrent slot filtering in sweeper threads. (patchset #4 id:60001 of https://codereview.chromium.org/2401563002/ )

Reason for revert:
Crashing.

Original issue's description:
> [heap] Concurrent slot filtering in sweeper threads.
>
> This is an intermediate step for concurrent slot filtering. This CL already makes filtering concurrent, but does not integrate it in the actual sweeping. This will be done in two follow up CLs. One for the regular slot set and one for the typed slot set.
>
> BUG=chromium:648568
>
> Committed: https://crrev.com/1f89d369fc952a2826f9f62901fb84fcf30920d7
> Cr-Commit-Position: refs/heads/master@{#40040}

TBR=ulan@chromium.org,mlippautz@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:648568

Review-Url: https://codereview.chromium.org/2399003002
Cr-Commit-Position: refs/heads/master@{#40043}