Check that the argument passed to %OptimizeOsr is smi before accessing
it. If it isn't an Smi we crash unless we are fuzzing. When fuzzing,
this returns early (turns into a Nop) if the argument isn't an Smi.

Bug: chromium:1071045
Change-Id: Iff1ee3e368dfffdbbbab4107dc355d5460b996e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2150602
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67195}