Most code comments use lowercase. This CL fixes the few that used
uppercase, for consistency.

R=thibaudm@chromium.org

Change-Id: Ib02c8202f049a968662c91ade2252df24326a943
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2308336Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68962}