num playbackRate

Source 

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

Source 

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