equals(sum, 0, "Timings must be non-zero");
      };
      const observer = new PerformanceObserver(list => {
        try {
          run_test(list);
          resolve();
        } catch(e) {
          reject(e);
        }
      });
      observer.observe({ entryTypes: ["resource"] });
      fetch(url);
    })}, "An opaque origin should be authorized to see resource timings when" +
         " the TAO header is the string 'null'");
  </` + `script></body>`;

frameContext.style = "display:none"
frameContext.s