num playbackRate

Source 

@DomName('AnimationEffectTiming.playbackRate')
@DocsEditable()
@Experimental() // untriaged
num get playbackRate =>
    _blink.BlinkAnimationEffectTiming.instance.playbackRate_Getter_(this);
void playbackRate=(num value)

Source 

@DomName('AnimationEffectTiming.playbackRate')
@DocsEditable()
@Experimental() // untriaged
set playbackRate(num value) => _blink.BlinkAnimationEffectTiming.instance
    .playbackRate_Setter_(this, value);