content-mathml.js modifies Presentation MathML (badly) [WAS: 2.5-beta: `content-mathml.js` and `mml3.js` clash]

If both extensions are loaded, I get rendering issues.

<math xmlns="http://www.w3.org/1998/Math/MathML">

<mstack>
  <mscarries crossout="downdiagonalstrike">
    <mn>2</mn>  <mn>12</mn>  <mscarry crossout="none"> <none/> </mscarry>
  </mscarries>
  <mn>2,327</mn>
  <msrow> <mo>-</mo> <mn> 1,156</mn> </msrow>
  <msline/>
  <mn>1,171</mn>
</mstack>
</math>

turned into

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mtable columnspacing="0em">
    <mtr>
      <mtd>
        <mover>
          <mphantom>
            <mn>0</mn>
          </mphantom>
          <mi>mpadded</mi>
        </mover>
      </mtd>
      <mtd>
        <mn>2</mn>
      </mtd>
      <mtd>
        <mn>,</mn>
      </mtd>
      <mtd>
        <mover>
          <menclose notation="downdiagonalstrike">
            <mn>3</mn>
          </menclose>
          <mpadded width="0em" lspace="-0.5width">
            <mn>2</mn>
          </mpadded>
        </mover>
      </mtd>
      <mtd>
        <mover>
          <menclose notation="downdiagonalstrike">
            <mn>2</mn>
          </menclose>
          <mpadded width="0em" lspace="-0.5width">
            <mn>12</mn>
          </mpadded>
        </mover>
      </mtd>
      <mtd>
        <menclose notation="none">
          <mn>7</mn>
        </menclose>
      </mtd>
    </mtr>
    <mtr>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mo>-</mo>
          </mpadded>
        </menclose>
      </mtd>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mn>1</mn>
          </mpadded>
        </menclose>
      </mtd>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mn>,</mn>
          </mpadded>
        </menclose>
      </mtd>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mn>1</mn>
          </mpadded>
        </menclose>
      </mtd>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mn>5</mn>
          </mpadded>
        </menclose>
      </mtd>
      <mtd>
        <menclose notation="bottom">
          <mpadded depth=".1em" height="1em" width=".4em">
            <mn>6</mn>
          </mpadded>
        </menclose>
      </mtd>
    </mtr>
    <mtr>
      <mtd>
        <mi>mtd</mi>
      </mtd>
      <mtd>
        <mn>1</mn>
      </mtd>
      <mtd>
        <mn>,</mn>
      </mtd>
      <mtd>
        <mn>1</mn>
      </mtd>
      <mtd>
        <mn>7</mn>
      </mtd>
      <mtd>
        <mn>1</mn>
      </mtd>
    </mtr>
  </mtable>
</math>