For some reason, the property wasn't already added. Oops!

BUG=v8:7815
R=gsathya@chromium.org, neis@chromium.org

Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I71898ca1e84ce930f5d0ed75e44c75071f152904
Reviewed-on: https://chromium-review.googlesource.com/1114327
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54032}