Apply the attached patch (note this is the patch for bug 1724901 along with test). Run the reftest from the patch

./mach reftest gfx/tests/reftest/ --enable-fission --enable-webrender

The text will differ significantly between the test/ref, it will probably be stretch horizontally, or shifted. (Note in the successful case the text will look visually the same but there might be some minor fuzz needed in the reftest.list file to make the test pass.)

Bisected to bug 1723665.

Glenn, would you mind taking a look at this? Hopefully the instructions to reproduce are clear and easy.

Sure, I'll take a look first thing tomorrow morning.

An example from try server https://hg.mozilla.org/mozilla-central/raw-file/tip/layout/tools/reftest/reftest-analyzer.xhtml#logurl=https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/dfg7ULX6SnK0rjrSv0w1Yg/runs/0/artifacts/public/logs/live_backing.log&only_show_unexpected=1

Set release status flags based on info from the regressing bug 1723665

The regressing bug was backed out, closing.