This CL fix typo in a comment introduced recently.
There is no functional change.

Bug: chromium:1091259
Change-Id: I56f1963514b87b2a93859a6db707be093e865e28
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2276748
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>