Handle fractions in KaTeX

[gnprice]

From our TeX content survey, at #mobile-team > KaTeX survey results @ 💬, @rajveermalviya writes:

"""

438 messages failed because of unsupported css class: mfrac.
406 messages failed because of unsupported css class: frac-line.

These are fractions, they depend on borders being implemented. Another characteristics we'll need to implement (but should be trivial) is to get the numerator and denominators to be in the center.
"""

This was the 8th item after all the functionality included in releases so far (#46 (comment)).

References

• Prerequisite: Handle borders (e.g. for overline) in KaTeX #1673
• Prerequisite: Handle nulldelimiter (spacing around e.g. fractions) in KaTeX #1677