<!doctype html>
<title>structured clone vs reference</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<script>
async_test(function(t) {
  var x = [];
  y = [x,x];
  postMessage(y, '*');
  onmessage = t.step_func(function(e) {
    assert_equals(e.data[0], e.data[1], 'e.data[0] === e.data[1]');
    assert_not_equals(e.data[0], x, 'e.data[0] !== x');
    t.done();
  });
});
</script>