Fix firefox scroll issue

lib/timeline/Range.js

@@ -611,7 +611,9 @@ export default class Range extends Component {
       // In Mozilla, sign of delta is different than in IE.
       // Also, delta is multiple of 3.
       delta = -event.detail / 3;
-    }
+    } else if (event.deltaY) {
+      delta = -event.deltaY / 3;
+    } 
 
     // don't allow zoom when the according key is pressed and the zoomKey option or not zoomable but movable
     if ((this.options.zoomKey && !event[this.options.zoomKey] && this.options.zoomable)