Honestly, there would be a bunch of other small pieces I'd want too, though...
the ability to count content characters in CSS `calc()`, for example. (So I could set the fraction digit display widths to be the same character count as every other one in the same form or column)
Or the ability to select an element that had textContext containing, startingWith, or matching something. (So I could make numbers with a sign of `-` a different color or something)