Flakily renders black.

Bug: angleproject:5875
Change-Id: I16805278e00d431bf81e531d5b0b17868ee8f476
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2833011Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>