This is short-term fix for flaky failures on GC fuzzer. The closures
g1 and g2 have the same SFI and pending optimzed table treats them as
a single entry. This cl, adds %PrepareFunctionForOptimize after one of
them is optimized.

Bug: v8:9556
Change-Id: I1fd72da1baa5de2f7650e080f9b6d04b69dd6a16
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1719188Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62934}