These are useful for the cases when an embedder works with backing
stores without creating JS ArrayBuffer objects.

Bug: v8:9380
Change-Id: I452bd911e7b20fb38568f18f9d15ea1a7ffb5a57
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1825339
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64460}