Revert of [heap] Unregister shrinked large object memory from chunk map. (patchset #6 id:100001 of https://codereview.chromium.org/2046953002/ )

Reason for revert:
Revert because uncommit of lo is broken.

Original issue's description:
> [heap] Unregister shrinked large object memory from chunk map.
>
> BUG=chromium:617883
> LOG=n
>
> Committed: https://crrev.com/2b38d3121b5fd0e409cdda0071fa2e0ec2846ab2
> Cr-Commit-Position: refs/heads/master@{#36793}

TBR=ulan@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:617883

Review-Url: https://codereview.chromium.org/2046563008
Cr-Commit-Position: refs/heads/master@{#36806}