Why does Chrome still use prefix for animations?

Question

I'm really not sure if this question should be here, if not, please forgive me, but I'm intrigued in the reason why Chrome/Safari still prefix CSS3 animations, given that any other major browser supports them as standart, some even since a long time. (IE +9, Firefox +15, Opera +12.0 according to this)

@keyframes anim{}
@-webkit-keyframes anim{}

div{
    animation:anim;
    -webkit-animation:anim;
}

Is it still considered an experimental technology?

Thanks!