Bug #163200 will fix most of the issues regarding minimum size of grid items.
But there's still one thing remaining related to transferred size of replaced elements.
The spec is: https://drafts.csswg.org/css-flexbox-1/#automatic-minimum-size
We haven't implemented anything regarding the transferred vs content size.
This will allows us to pass 2 tests from the W3C suite:
This has been fixed already in r213480 (bug #169203).
That patch was importing: https://chromium.googlesource.com/chromium/src/+/ab779b340b6d4170920e1cf2ce50e67f64d67fac