Formerly, we zapped a transition array when we replaced it with a
larger one, but this is no longer necessary. Leaving those arrays in
peace makes life easier for concurrent (racy) access from a background
compilation thread.

Design doc with more info about racy access to transition arrays
between the main JavaScript thread and a background compilation thread
here:
https://docs.google.com/document/d/1ax2qyENdr50Qu9yur1qNu6_zRK0m6K2l7BLM_QDBFJM/edit?usp=sharing

Change-Id: I4c2757945266d43d82ec157e0ff2b9208a8e4c63
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2253840Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68437}