The Tor Browser / file revision

 // Any copyright is dedicated to the Public Domain.

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

 var BUGNUMBER = 373118;

 var summary =

   'Properly handle explicitly-undefined optional arguments to a bunch of ' +

   'functions';

 print(BUGNUMBER + ": " + summary);

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

 var a;

 a = "abc".slice(0, undefined);

 assertEq(a, "abc");

 a = "abc".substr(0, undefined);

 assertEq(a, "abc");

 a = "abc".substring(0, undefined);

 assertEq(a, "abc");

 a = [1, 2, 3].slice(0, undefined);

 assertEq(a.join(), '1,2,3');

 a = [1, 2, 3].sort(undefined);

 assertEq(a.join(), '1,2,3');

 assertEq((20).toString(undefined), '20');

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

 reportCompare(true, true);