I think these got disabled when trying to green up tests on the new version of macos. However I think they were failing when the machines were still configured with disappearing scrollbars and weren't re-evaluated when the machines (correctly) had disappearing scrollbars disabled.
One needs this magic incantation in order to push to try currently with these new machines
./mach try fuzzy --worker-override="t-osx-1015-r8=releng-hardware/gecko-t-osx-1400-r8-staging" -q 'test-macosx1015 ...'
Differential Revision: https://phabricator.services.mozilla.com/D231906
be9c15aa26