Fix Group Performance (#3453)

* Implement group redraw @grimalschi performance enhancement

* Fix JSDoc for redraw

* Remove commented out in itemset

* Remove fasdom

* Clean up queue functions in group redraw

* Fix mistake in comments

* Remove extra read-write from _didResize

* Resolve review comments

* Fix ranged item resizing bug

* remove parameter that wasn;t used

lib/timeline/component/Group.js

@@ -285,7 +285,7 @@ Group.prototype._applyGroupHeight = function(height) {
 }
 
 // update vertical position of items after they are re-stacked and the height of the group is calculated
-Group.prototype._updateItemsVerticalPosition = function(resized, margin) {
+Group.prototype._updateItemsVerticalPosition = function(margin) {
   for (var i = 0, ii = this.visibleItems.length; i < ii; i++) {
     var item = this.visibleItems[i];
     item.repositionY(margin);
@@ -293,12 +293,6 @@ Group.prototype._updateItemsVerticalPosition = function(resized, margin) {
       if (item.displayed) item.hide();
     }
   }
-
-  if (!this.isVisible && this.height) {
-    return false;
-  }
-
-  return resized;
 }
 
 /**
@@ -360,8 +354,15 @@ Group.prototype.redraw = function(range, margin, forceRestack, returnQueue) {
 
     // update vertical position of items after they are re-stacked and the height of the group is calculated
     (function() {
-      return resized = this._updateItemsVerticalPosition.bind(this)(resized, margin)
-    }).bind(this)
+      this._updateItemsVerticalPosition.bind(this)(margin)
+    }).bind(this),
+
+    function() {
+      if (!this.isVisible && this.height) {
+        resized = false;
+      }
+      return resized
+    }
   ]
 
   if (returnQueue) {