[csswg-drafts] text-spacing is very complicated (#4246)

litherum has just created a new issue for https://github.com/w3c/csswg-drafts:

== text-spacing is very complicated ==
`text-spacing` is getting very complicated now. By my count, the current grammar accepts 769 different combinations of values (770 if you count [`auto`](https://github.com/w3c/csswg-drafts/issues/3229#issuecomment-431806206)). It's probably worth an investigation to determine which of these combinations are actually useful.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4246 using your GitHub account