chromium/src/third_party/blink/web_tests/external/wpt/fetch/api/basic/mediasource.window.js

promise_test(t => {
  const mediaSource = new MediaSource(),
        mediaSourceURL = URL.createObjectURL(mediaSource);
  return promise_rejects_js(t, TypeError, fetch(mediaSourceURL));
}, "Cannot fetch blob: URL from a MediaSource");