The Tor Browser / file revision

 // Test corner cases of for-of iteration over Arrays.

 // The current spidermonky JSOP_SPREAD implementation for function calls

 // with '...rest' arguments uses a ForOfIterator to extract values from

 // the array, so we use that mechanism to test ForOfIterator here.

 //

 // Check case where ArrayIterator.prototype.next changes in the middle of iteration.

 //

 function TestChangeArrayIteratorNext() {

     function doIter(f, arr) {

         return f(...arr)

     }

     function fun(a, b, c) {

         var result = 0;

         for (var i = 0; i < arguments.length; i++)

             result += arguments[i];

         return result;

     }

     var GET_COUNT = 0;

     function getter() {

         GET_COUNT++;

         if (GET_COUNT == MID)

             iterProto.next = NewNext;

         return M2;

     }

     var iter = ([])['@@iterator']();

     var iterProto = Object.getPrototypeOf(iter);

     var OldNext = iterProto.next;

     var NewNext = function () {

         return OldNext.apply(this, arguments);

     };

     var TRUE_SUM = 0;

     var N = 100;

     var MID = N/2;

     var M = 3;

     var arr = new Array(M);

     var ARR_SUM = 0;

     for (var j = 0; j < M; j++) {

         arr[j] = j;

         ARR_SUM += j;

     }

     var M2 = (M/2)|0;

     Object.defineProperty(arr, M2, {'get':getter});

     var sum = 0;

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

         sum += doIter(fun, arr);

         TRUE_SUM += ARR_SUM;

     }

     assertEq(sum, TRUE_SUM);

 }

 TestChangeArrayIteratorNext();

 if (typeof reportCompare === "function")

   reportCompare(true, true);