[luatex] [NTG-context] Problem with luaotfload and positioning of primes

[Jura Pintar]

> Can you post an MWE? I'll have to check what that looks like at
> the Luaotfload end. IIUC the size "feature" shouldn't conflict
> with other features because it's somewhat eccentric, to put it
> mildly.

Turns out I was a bit hasty: I've now replicated the problem without optical
sizes, too. Here is an MWE with Latin Modern:

\documentclass{article}
\usepackage{unicode-math}
\begin{document}

\small
$x' x''x'''$ vs. $x\prime x\dprime x\trprime$

\normalsize
$x' x''x'''$ vs. $x\prime x\dprime x\trprime$

\Large
$x' x''x'''$ vs. $x\prime x\dprime x\trprime$

\end{document}

It looks as though the ssty feature isn't being applied above a size
cut-off. 

> But then, what math font comes in optical sizes?

Johannes Kuester's Minion Math (http://typoma.de/en/fonts.html) is the only
one, as far as I know.

Best,

Jura