Skip WebGL2CompatibilityTest.CopyMip1ToMip0 on Mac Intel GL Flaky. Aleady skipped on Win Intel GL. Bug: angleproject:4805 Change-Id: I206d66079ca4beabfee12f6c9989d960ca461877 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2347463 Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>