[is.html]
  [Invalidate :is() for simple selector arguments.]
    expected: FAIL

  [Invalidate :is() for compound selector arguments.]
    expected: FAIL

  [Invalidate :is() for complex selector arguments.]
    expected: FAIL

  [Invalidate nested :is().]
    expected: FAIL

  [Test specificity of :is().]
    expected: FAIL