A negative value for animation-duration and transition-duration should be treated as 0s.
Created attachment 138051 [details]
Comment on attachment 138051 [details]
The spec issue hasn't been settled yet: https://www.w3.org/Bugs/Public/show_bug.cgi?id=16806
it is stated that :
"A negative ‘animation-duration’ value renders the declaration invalid." which is what WebKit does today. I can close the bug.