To make it obvious these are not defined in C++.

Bug: v8:7793
Change-Id: Ib846023992e32ddd10dadc3834ce42b7604a1f48
Reviewed-on: https://chromium-review.googlesource.com/c/1495993Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59978}