define([
  	"../../core",
  	"../../selector"
  	// css is assumed
  ], function( jQuery ) {
  
  	return function( elem, el ) {
  		// isHidden might be called from jQuery#filter function;
  		// in that case, element will be second argument
  		elem = el || elem;
  		return jQuery.css( elem, "display" ) === "none" || !jQuery.contains( elem.ownerDocument, elem );
  	};
  });