Drive-by change: fix stray "//".

R=clemensb@chromium.org

Change-Id: I614bbc545ab8cd803f0c64f04e01fa55c4c2ec7b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3605610Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80182}