 <munderover>,
       <mmultiscripts>, <mfrac> are not embellished
       operators if their first in-flow child is not an embellished operator -->
  <p>
    <math>
      <mn>X</mn>
      <msub class="testedElement">
        <mn>X</mn>
        <mo lspace="2em" rspace="0em">X</mo>
      </msub>
      <mn>X</mn>
    </math>
  </p>
  <p>
    <math>
      <mn>X</mn>
      <msup class="testedElement">
        <mn>X</mn>
        <mo lspace="2em" rspace="0em">X</mo>
      </msup>
      <mn>X</mn>
    </math>
  </p