[luatex] Use Math Glyphs from Text Font

[C. Comren]

> There must be some other case for the issue you have, and without a
> minimal example one can hardly tell.

This example,

  \documentclass{article}
  \usepackage{unicode-math}
  \setmathfont[range=\mathbfsfit/{greek,Greek}]{AFontWithGreekGlyphs}
  \begin{document}
  \[
    d \beta = \omega
  \]
  \end{document}

produces a PDF without \beta and \gamma.