Fix incorrect verification for SimultaneousUploadAndDraw MultithreadingTestES3.SimultaneousUploadAndDraw was verifying its results incorrectly, resulting in incorrect failures. Bug: angleproject:8341 Change-Id: Ie9268391c7b65a904a05c428c13be1041e8a7383 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5647496 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>