Fix original imlpementation to support occurrence in eval(), and unskip
tests.

BUG=v8:8523
r=gsathya@chromium.org, mathias@chromium.org, littledan@chromium.org

Change-Id: I80a3e8623357947c564a6cdf865eeff435b8e640
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1510792Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#60246}