This is deprecated in C++20.  Use constexprs and explicit casts to work
around.

Bug: chromium:1284275
Change-Id: I6a3974f3c678cb797081938622036a12a99c5d1b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3630349
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80392}