Fix comment typo

lib/timeline/component/item/RangeItem.js

@@ -45,11 +45,11 @@ RangeItem.prototype.isVisible = function(range) {
   // determine visibility
 var isVisible = 
 // determine horizontal visibillity
-  (this.data.start < range.end) && 
-  (this.data.end > range.start) && 
-// determine verticaltal visibillity
-  (this.parent.top < range.body.domProps.centerContainer.height - range.body.domProps.scrollTop) && 
-  (this.parent.top + this.parent.height > - range.body.domProps.scrollTop)
+(this.data.start < range.end) && 
+(this.data.end > range.start) && 
+// determine vertical visibillity
+(this.parent.top < range.body.domProps.centerContainer.height - range.body.domProps.scrollTop) && 
+(this.parent.top + this.parent.height > - range.body.domProps.scrollTop)
 return isVisible;};
 
 /**