Revert of Lazily register prototype users (patchset #2 id:20001 of https://codereview.chromium.org/1104813004/)

Reason for revert:
Suspected of causing GC stress failures.

Original issue's description:
> Lazily register prototype users
>
> when handing out validity cells to handles; because invalidating said cells is the only time we'll need the user registrations.
> Along the way, fix a corner case in WeakFixedArray, which can now be empty after the recently introduced compaction support.
>
> Committed: https://crrev.com/a4bb7643c076b014816431a9b85af3e2edf828e7
> Cr-Commit-Position: refs/heads/master@{#28047}

TBR=yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1108583002

Cr-Commit-Position: refs/heads/master@{#28049}