Mark 'math-style' and 'math-depth' as "font-affecting properties" #339

CSS recently added the concept of "font-affecting properties", which is any property that can adjust the font metrics on an element which are depended on for the font-relative units like em or cap. (This term lets us be more precise about which properties need to trigger cycle-avoidance behavior if you use the font-relative units in them; see CSSWG Issue 14306.)

The 'math-style' and 'math-depth' properties in MathML both qualify here, since they can adjust the 'font-size' of the element. Would you mind putting in a statement somewhere defining that these two properties are font-affecting properties?

You can do it in an early general section, like Fonts 4 does since it has a bunch of them, or just have a sentence somewhere in those properties' individual definition sections.