Fix infinite animation iterations inside a group by shortcutting time fraction calculation.
Fix infinite animation iterations inside a group by shortcutting time
fraction calculation.

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