, '');
      t.step_timeout(function() {
        if (src == '') {
          assert_equals(e.currentSrc, '');
        } else {
          assert_equals(e.currentSrc, s.src);
        }
        t.done();
      }, 0);
    }, tagName + '.currentSrc after adding source element with src attribute "' + src + '"');
  });
});
</script>
