R=titzer@chromium.org
TEST=mjsunit/regress/regress-crbug-969368
BUG=chromium:969368

Change-Id: If8cdd3a170c3c0e487daa2c2dd9e347fb8eabafd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1662571Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62226}