When I use css('animation-iteration-count', 5) I expect element has style="-webkit-animation-iteration-count: 5;" (this vendor prefix is just a example), but it doesn't.

So I debug jQuery.js, I found when I use css('animation-iteration-count', 5) actually become style[ 'WebkitAnimationIterationCount' ] = 5 + 'px'.
Browser consider it a illegal value, because animation-iteration-count only accept infinite | <number>, so this style don't have effect.

This is a reproduceBug demo

So that cssNumber shoud add animationIterationCount property to prevent automatically add "px" to the value.