texmath-0.13.1.2: test/writer/mml/mfrac2.test

<<< native
[ EFraction
    NormalFrac
    (ESymbol Ord "\8518")
    (EGrouped [ ESymbol Ord "\8518" , EIdentifier "x" ])
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mfrac>
    <mi>ⅆ</mi>
    <mrow>
      <mi>ⅆ</mi>
      <mi>x</mi>
    </mrow>
  </mfrac>
</math>