Make Timing mutable and calculated properties on TimedItem read only
Make Timing mutable and calculated properties on TimedItem read only

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