[CommonHTML] Safari extraneous space in mover

Reported via the user group.

Using the CommonHTML output, Safari 9 and 10 add extra space to the right of an mover; HTML-CSS and SVG seem ok. This might be a browser bug.

Example.

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow class="MJX-TeXAtom-ORD">
    <mover>
      <mi>u</mi>
      <mo stretchy="false">&#x2192;<!-- → --></mo>
    </mover>
  </mrow>
  <mo>+</mo>
  <mrow class="MJX-TeXAtom-ORD">
    <mover>
      <mi>v</mi>
      <mo stretchy="false">&#x2192;<!-- → --></mo>
    </mover>
  </mrow>
</math>