svg/as-object/svg-in-object-dynamic-attribute-change.html very frequently fails, especially on slower bots: https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#tests=svg%2Fas-object%2Fsvg-in-object-dynamic-attribute-change.html The failure is super strange - some of the squares are only partially painted, or even are overpainted (?!)
Debugging this is complicated by bug 148923, as repeating the test multiple times doesn't work.
Added a test expectation in r189456.