[at-position-try-parse.html]
  [@position-try --foo { } should be a valid rule]
    expected: FAIL

  [@position-try --foo { top: 1px; } should be a valid rule]
    expected: FAIL

  [@position-try --foo { backround-color: green; } should be a valid rule]
    expected: FAIL

  [@position-try --foo { @keyframes bar {} } should be a valid rule]
    expected: FAIL

  [@position-try --foo { @font-face {} } should be a valid rule]
    expected: FAIL

  [@position-try --foo { @media print {} } should be a valid rule]
    expected: FAIL

  [@position-try --foo { & {} } should be a valid rule]
    expected: FAIL

  [@position-try --foo { arbitrary garbage } should be a valid rule]
    expected: FAIL