Println format string padding variable syntax $ not highlighted

[eugenesvk]

println!("{:>6}",6); this is highlighted
println!("{:>pad$}",5,pad=_xx); this isn't though also should
The format-escapes rule seems to be missing the fact that count can be an identifier, not just a number
width := count
count := parameter | integer
parameter := argument '$'
argument := integer | identifier

so count := (integer | identifier) '$'?

(same for precision := count | '*')