The Tor Browser / file revision

 function testInt32ToId()

 {

   // Ensure that a property which is a negative integer that does not fit in a

   // jsval is properly detected by the 'in' operator.

   var obj = { "-1073741828": 17 };

   var index = -1073741819;

   var a = [];

   for (var i = 0; i < 10; i++)

   {

     a.push(index in obj);

     index--;

   }

   // Ensure that a property which is a negative integer that does not fit in a

   // jsval is properly *not* detected by the 'in' operator.  In this case

   // wrongly applying INT_TO_JSID to -2147483648 will shift off the sign bit

   // (the only bit set in that number) and bitwise-or that value with 1,

   // producing jsid(1) -- which actually represents "0", not "-2147483648".

   // Thus 'in' will report a "-2147483648" property when none exists, because

   // it thinks the request was really whether the object had property "0".

   var obj2 = { 0: 17 };

   var b = [];

   var index = -(1 << 28);

   for (var i = 0; i < 10; i++)

   {

     b.push(index in obj2);

     index = index - (1 << 28);

   }

   return a.join(",") + b.join(",");

 }

 assertEq(testInt32ToId(),   

 	 "false,false,false,false,false,false,false,false,false,true" +

 	 "false,false,false,false,false,false,false,false,false,false");