Use transition events

[markcellus]

Looks like we can possibly simplify the library and use transition events now that transitioncancel and transitionrun events are available? We can try this suggestion from @birtles.

[birtles]

Note that Safari 13.1 has just shipped with support for Web Animations including getAnimations(). Also Firefox 75 will ship support for getAnimations() in the next day or two. So you could potentially also have a codepath for browsers that support getAnimations().

[markcellus]

Thanks for that info! Will take a closer look once I get some time. ❤️