Reland of [heap] Cleanup mark bit usage. (patchset #1 id:1 of https://codereview.chromium.org/1490753003/ )

Reason for revert:
Reland after fixing the potential root cause of the canary crasher.

Original issue's description:
> Revert of [heap] Cleanup mark bit usage. (patchset #1 id:1 of https://codereview.chromium.org/1474203003/ )
>
> Reason for revert:
> Still investigating bad canary.
>
> Original issue's description:
> > [heap] Cleanup mark bit usage.
> >
> > BUG=
> >
> > Committed: https://crrev.com/5874ac783ff9bc4bb4b2fda81f5077f06619f96c
> > Cr-Commit-Position: refs/heads/master@{#32362}
>
> TBR=mlippautz@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=
>
> Committed: https://crrev.com/d3faef8658598e68331208b5a1846ac1c250cb49
> Cr-Commit-Position: refs/heads/master@{#32461}

TBR=mlippautz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1488393003

Cr-Commit-Position: refs/heads/master@{#32502}