FontFace.sizeAdjust missing?

[Josh-Cena]

IIUC, FontFace properties is supposed to correlate 1-1 with @font-face descriptors. However sizeAdjust (for size-adjust) is missing in the spec, while it's implemented in all three browsers.

I'm reading https://drafts.csswg.org/css-font-loading/#fontface-interface and this issue comes out of mdn/content#36587

[cdoublev]

@font-face descriptors are defined in both CSS Fonts 4 and 5. size-adjust is only defined in CSS Fonts 5 at the moment, so my best guess is that it will be added as a FontFace attribute when backported to CSS Fonts 4.