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chromium/third_party/blink/web_tests/external/wpt/html/semantics/links/links-created-by-a-and-area-elements/support/target_blank_implicit_noopener.html 

<!DOCTYPE html>
<script>
  let bc = new BroadcastChannel(window.location.search.substring(1));
  bc.postMessage({ hasOpener: opener !== null });
  window.close();
</script>