CSS sprite sheet animation

HTML

<img src="http://s.cdpn.io/79/sprite-steps.png" />
<div class="hi"></div>

CSS

.hi {
    width: 50px;
    height: 72px;
    background-image: url("http://s.cdpn.io/79/sprite-steps.png");
    /*    
    -webkit-animation: play .8s steps(10) infinite;
       -moz-animation: play .8s steps(10) infinite;
        -ms-animation: play .8s steps(10) infinite;
         -o-animation: play .8s steps(10) infinite;
            animation: play .8s steps(10) infinite;
    */
}

/*
@-webkit-keyframes play {
   from { background-position:    0px; }
     to { background-position: -500px; }
}

@-moz-keyframes play {
   from { background-position:    0px; }
     to { background-position: -500px; }
}

@-ms-keyframes play {
   from { background-position:    0px; }
     to { background-position: -500px; }
}

@-o-keyframes play {
   from { background-position:    0px; }
     to { background-position: -500px; }
}

@keyframes play {
   from { background-position:    0px; }
     to { background-position: -500px; }
}
*/

JavaScript

// Sprite Sheet animation with Web Animations.
// Forked from: http://jsfiddle.net/simurai/CGmCe/light/

document.querySelector('.hi').animate([
    {
        backgroundPosition: "0px"
    },
    {
        backgroundPosition: "-500px"
    }
], {
    duration: 800,
    iterations: Infinity,
    easing: 'steps(10)'
});