Better to do this after webidl-fication.
Created attachment 745567 [details] [diff] [review]
Comment on attachment 745567 [details] [diff] [review]
Could you add an assertion at the start of
!aAnimation == !aEa && !aAnimation == !aEventsToDispatch.
I'm surprised the 0.5 is in quotes. Does that work?
And again, it would be good to remove initAnimationEvent in a followup patch.
Created attachment 745639 [details] [diff] [review]
I didn't changed:
because the new fourth optional arguments never went into a release as the method has been removed by bug 868751 (that is still in progress to be documented).