This was triggering when parentGroup.iterationTime == 0, which was causing forward fill of reversed animations to fail (test-start-time.html and test-start-time-tierations.html picked this up).
This was triggering when parentGroup.iterationTime == 0, which was causing forward fill of reversed animations to fail (test-start-time.html and test-start-time-tierations.html picked this up).

web-animations/web-animations-js-legacy,beni55/web-animations-js-legacy,web-animations/web-animations-js-legacy,birtles/web-animations-js,dstockwell/web-animations-js,dstockwell/web-animations-js,web-animations/web-animations-js-legacy,beni55/web-animations-js-legacy,beni55/web-animations-js-legacy,beni55/web-animations-js-legacy,birtles/web-animations-js,birtles/web-animations-js