Test for non-string objects in the CheckedInternalizedString slow path.

Bug: v8:7700
Change-Id: Iac82a39ad0a0a93b328f8c574ed0bb7e2f39703b
Fixed: chromium:1360432
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3879227
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83040}