Revert of [elements] Minor hardening and cleanup of concat (patchset #7 id:120001 of https://codereview.chromium.org/1812753004/ )

Reason for revert:
[Sheriff] Something seems to leak:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20ASAN/builds/10838

I don't see the direct connection to this CL though...

Original issue's description:
> [elements] Minor hardening and cleanup of concat
>
> BUG=
>
> Committed: https://crrev.com/b98b3fbbe3dd14548cb356339f52403c07ef33f4
> Cr-Commit-Position: refs/heads/master@{#35027}

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

Review URL: https://codereview.chromium.org/1825363002

Cr-Commit-Position: refs/heads/master@{#35028}