We consider some function "test-only" function, e.g. if they have a
"ForTesting" in their name. The src/runtime/runtime-test.cc file should
be allowed to call such functions.

R=tmrts@chromium.org
CC=ahaas@chromium.org

Change-Id: Ib57bba36ba35f29c7673d4cef6d6b1e5ad9c7f65
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2339623Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69308}