MathJax_Preview causes extra line break in Firefox within list items

From a user report elsewhere.

If one starts a list item <li> with a mathjax alignment structure, the equations will become vertically centered with respect to the list item in Chrome and top aligned in Firefox. You can see this in https://cdi2tp.math.tecnico.ulisboa.pt/enunciados/ExameAsol2015160627.php if you open the second collapsed <details>.

Firefox:

Chrome

I haven't had a chance to take a closer look, so labeling it investigate.