Firefox NativeMML does not stretch direct child operators of an mtd/math

[fred-wang]

This is bug 236963 in Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=236963

The bug does not show up with the math element because we always add an explicit mrow. Regarding the mtd element, the situation does not seem to be very likely for the TeX input jax. Here is one where I cheated and used \mmlToken:

  \(
  \begin{array}{c}
    \mmlToken{mo}{[}
    \Space{0em}{1em}{1em}
  \end{array}
  \)

[fred-wang]

A workaround for this is available on #356

[dpvc]

This seems to be working now (tested in FF 25).