memcpy doesn't like being called with dest=nullptr and size=0.

Change-Id: Ie01991834a867991ff51287cbe43d22f636b800e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781695Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63529}