fix: Range.js "event" is undeclared (#2749)

lib/timeline/Range.js

@@ -843,7 +843,7 @@ Range.prototype.moveTo = function(moveTo) {
   var newStart = this.start - diff;
   var newEnd = this.end - diff;
 
-  this.setRange(newStart, newEnd, false, true, event);
+  this.setRange(newStart, newEnd, false, true, null);
 };
 
 module.exports = Range;