This was showing up as a GN error with a newer version of GN.

Bug: angleproject:3792
Change-Id: I1993ccfe079c1768217f704cc9ba036ec67024bf
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1745226Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>