This typo was hidden behind a THREAD_SANITIZER flag so it was uncaught
by the CQ. I verified this fix locally.

Bug: chromium:1097082
Change-Id: I4e31d1d1253cbcaf292c9a588bcd54fc298e85b6
TBR=jmadill@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2254558Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>