I have a patch with a layout test that fails on mac_chromium_rel_ng but it is reported as "pass" on the mac_chromium_rel_ng bot:
https://ci.chromium.org/p/chromium/builders/luci.chromium.try/mac_chromium_rel_ng/106170

Is this because "webkit_layout_tests" is marked as experimental? That seems like a bug because we should run layout tests on mac.