Fix early fragment tests optimization condition. The optimization should check of "alpha to coverage" is enabled, not just sample coverage. Bug: angleproject:4508 Bug: angleproject:5045 Bug: b/168493024 Change-Id: I0e52ddd4c92f9a6ea8a0e7cf56db71ce9ff3c5de Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2422078 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>