Since we're using compass, we can replace the body of this mixin with just:
```
@include experimental(animation-duration, $duration, -moz, -webkit, not -o, not -ms);
@include experimental(animation-fill-mode, forwards, -moz, -webkit, not -o, not -ms);
@include experimental(animation-name, $name, -moz, -webkit, not -o, not -ms);
```
And it will generate all of the rules for us.