[server-initiated.window.html]
  [`fetch()`: Invalid signature, same-origin: blocked.]
    expected: FAIL

  [`fetch()`: Invalid signature, cross-origin w/o cors, mode: no-cors: blocked.]
    expected: FAIL

  [`fetch()`: Invalid signature, same-origin w/ cors: blocked.]
    expected: FAIL

  [`fetch()`: Invalid signature, cross-origin w/ cors, mode: no-cors: blocked.]
    expected: FAIL

  [`fetch()`: Invalid signature, cross-origin w/ cors, mode: cors: blocked.]
    expected: FAIL