src/third_party/mozjs-45/js/src/jit-test/tests/basic/testSlowArrayLength.js

function testSlowArrayLength()
{
  var counter = 0;
  var a = [];
  a[10000 - 1] = 0;
  for (var i = 0; i < a.length; i++)
    counter++;
  return counter;
}
assertEq(testSlowArrayLength(), 10000);