[web-animations] Fix references to 'keyframe input' in Normalizing a Keyframe object procedure

--HG--
extra : rebase_source : 31e2ff70db5ed06b562dcb3e199c4f8edc8a379f
[web-animations] Thoroughly rewrite the procedures for handling the effect parameter for the Animation ctor and Animatable.animate method

And simultaneously remove OneOrMoreKeyframes since its not valid WebIDL and
generally tighten up our procedures for handling non-WebIDL ECMAScript objects.

--HG--
extra : rebase_source : 6f83de7842f9f898a8359e2b83e8a6673b78a800
[web-animations] Fix some broken links
[web-animations] Rename TimedItem.specified to timing