According to Flexbox and Grid Layout specs, the default value for the min-width/height properties for the flex/grid items should be 'auto'.
For flexbox items the default value was changed from min-content to 0 in https://bugs.webkit.org/show_bug.cgi?id=111790 and later reported as a regression https://bugs.webkit.org/show_bug.cgi?id=114566.
Since then the spec has changed and now it's clearly specified both the default value for those properties and also how to compute the minimum size for flex/grid items.
This requires intrinsic sizes support for height, min-height and max-heigt, see bug 113610.
The fix involves merging the following Blink change logs:
* for flexbox
* for grid
* for both
That's why I'm converting this into a meta-bug to land flex and grid changes independently
Closing as all dependent bugs were fixed.