(t => {
  var iframe = document.createElement('iframe');
  iframe.src = "/document-policy/echo-policy.py?id=3";
  iframe.policy = "lossless-images-max-bpp=0.9";
  callbacks["3"] = t.step_func_done(result => {
    assert_equals(result, "lossless-images-max-bpp=0.9");
  });
  document.body.appendChild(iframe);
}, "Child frame may have a stricter policy than the parent.");

async_test(t => {
  var iframe = document.createElement('iframe');
  iframe.src = "/document-policy/echo-policy.py?id=4";
  iframe.policy 