[css-grid-3][Masonry] Auto repeat and other intrinsic track sizes #12580
Description
In css-grid-3 is a tentative definition for sizing auto tracks within an auto repeat.
This means that repeat(auto-fill, auto) would be valid, but would auto repeat(auto-fill, auto) auto also be valid? If this should be valid, what about auto min-content repeat(auto-fill, auto) auto max-content or auto repeat(auto-fill, 100px) auto?
Currently, per css-grid-2, we force all tracks outside of an auto-repeat to be fixed. This potentially doesn't need to be the case, but I'm inclined to believe we should maintain this rule, even if we resolve to allow intrinsic repeaters, since that would incur quite a bit more complexity to the algorithm, and I'm not sure there is a good use case for this.