setBaseAndExtent as implemented in WebKit/Blink are related to these. Is the plan to drop the attributes but keep the function? Use counter data from Chrome: https://www.chromestatus.com/metrics/feature/timeline/popularity/400 https://www.chromestatus.com/metrics/feature/timeline/popularity/401 https://www.chromestatus.com/metrics/feature/timeline/popularity/402 https://www.chromestatus.com/metrics/feature/timeline/popularity/403 https://www.chromestatus.com/metrics/feature/timeline/popularity/406 Based on this dropping the attribute looks doable, but is WebKit going to?