The teardown/on-end handling of the download indicator "notification" (DownloadsIndicatorView.showEventNotification) is currently triggered by a setTimeout, using a duration value copied/calculated from the sum of the animations' durations defined in CSS. Its not clear at this point why a setTimeout is used rather than an animationend handler. If we switch to using animationend, care needs to be taken as animation may be occurring on both the indicator (button) as well as the notification element, and multiple animation names may need to be checked off before animation is considered complete.

:paolo, (non-urgent) can you comment on the history of this code, and any potential pitfalls you would anticipate with switching to an animationend event handler instead of the setTimeout used in showEventNotification?