fix(position): correct scrollbar width calculation

Closes #6273

Author: JuliaUsanova

src/position/position.js

@@ -130,7 +130,7 @@ angular.module('ui.bootstrap.position', [])
         var paddingRight = this.parseStyle(elemStyle.paddingRight);
         var paddingBottom = this.parseStyle(elemStyle.paddingBottom);
         var scrollParent = this.scrollParent(elem, false, true);
-        var scrollbarWidth = this.scrollbarWidth(scrollParent, BODY_REGEX.test(scrollParent.tagName));
+        var scrollbarWidth = this.scrollbarWidth(BODY_REGEX.test(scrollParent.tagName));
 
         return {
           scrollbarWidth: scrollbarWidth,