The Tor Browser / file revision

 // |reftest| skip-if(!xulRuntime.shell)

 // Any copyright is dedicated to the Public Domain.

 // http://creativecommons.org/licenses/publicdomain/

 //-----------------------------------------------------------------------------

 var BUGNUMBER = 843004;

 var summary =

   "Use of an object that emulates |undefined| as the sole option must " +

   "preclude imputing default values";

 print(BUGNUMBER + ": " + summary);

 if (typeof Intl !== 'object' && typeof quit == 'function') {

   print("Test skipped");

   reportCompare(true, true);

   quit(0);

 }

 /**************

  * BEGIN TEST *

  **************/

 var opt = objectEmulatingUndefined();

 opt.toString = function() { return "long"; };

 var str = new Date(2013, 12 - 1, 14).toLocaleString("en-US", { weekday: opt });

 // Because "weekday" was present and not undefined (stringifying to "long"),

 // this must be a string like "Saturday" (in this implementation, that is).

 assertEq(str, "Saturday");

 if (typeof reportCompare === "function")

   reportCompare(true, true);

 print("Tests complete");