Revert of [heap] Do not invoke GC to make heap iterable. (patchset #3 id:40001 of https://codereview.chromium.org/1992913004/ )

Reason for revert:
[Sheriff] Speculative revert for some flakes on the waterfall:
https://build.chromium.org/p/client.v8/builders/V8%20Mac%20-%20debug/builds/7409
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20-%20avx2/builds/7983
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20-%20internal%20snapshot/builds/4901

Original issue's description:
> [heap] Do not invoke GC to make heap iterable.
>
> This reverts commit 0aa3707d.
>
> And removes the UnreachableObjectsFilter.
>
> BUG=chromium:580959
> LOG=n
>
> Committed: https://crrev.com/132f89800f560190b4d655adcb4e0eeedd17fd82
> Cr-Commit-Position: refs/heads/master@{#36617}

TBR=yangguo@chromium.org,ulan@chromium.org,hpayer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:580959

Review-Url: https://codereview.chromium.org/2020363002
Cr-Commit-Position: refs/heads/master@{#36622}