The Tor Browser / file revision

 function test1() {

     var dense = [1, 2, 3];

     var denseHoles = [1, , 3];

     var result = 0;

     for (var i = 0; i < 70; i++) {

         if (i in dense) result += 1;

         if (1 in dense) result += 2;

         if (3 in dense) result += 3;

         if (-1000 in dense) result += 4;

         if (i in denseHoles) result += 5;

         if (1 in denseHoles) result += 6;

     }

     assertEq(result, 153);

 }

 test1();

 function test2() {

     var a = [1, 2, 3];

     for (var i = 0; i < 70; i++) {

         assertEq(-0 in a, true);

         assertEq(Math.sqrt(4) in a, true);

         assertEq(1.9 in a, false);

         assertEq(NaN in a, false);

         assertEq(Infinity in a, false);

     }

 }

 test2();

 function test3() {

     var a = [1, , 3];

     for (var i = 0; i < 70; i++) {

         if (i == 60)

             Object.prototype[1] = null;

         assertEq(1 in a, i >= 60);

     }

 }

 test3();