It shipped in Chrome 70.

Bug: v8:7807, v8:8562
Change-Id: I5c5a9fc23656018ee6e9115af7a0c779230e681b
Reviewed-on: https://chromium-review.googlesource.com/c/1450787
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59589}