BUG=v8:6949,v8:9396,chromium:1004912

Change-Id: Ifa8207283aadad258281bffda6d49da574402a24
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1809370
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63865}