This is in anticipation of more reference types from various proposals
being implemented.

Change-Id: I740ceeb3b6d6fc484a61f9ebee2181dbd6694440
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2243213Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68363}