The serializer clears JSFunctions together with feedback vectors
assuming that there is one to one correspondence between them.

That does not work in the case when there are multiple JSFunctions
sharing the same feedback vector. This patch ensures that all such
JSFunctions are properly cleared.

Bug: v8:7857
Change-Id: Ie441089e12bda5a8be7f9bed90f7be9499938609
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1698383Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62673}