[css-align] The 'alignment baseline' is undefined for Grid/Flexbox

[MatsPalmgren]

https://drafts.csswg.org/css-align-3/#baseline-export says

The alignment baseline is one of these, usually the dominant baseline associated with the shared alignment context. (See the dominant-baseline and alignment-baseline properties in [CSS-INLINE-3].)

https://drafts.csswg.org/css-inline/#dominant-baseline-property says

Applies to: block containers and inline boxes

So, it's undefined which 'alignment baseline' to use for grid/flex items since dominant-baseline doesn't apply to grid/flexbox containers. (I'm assuming for now that it is the dominant-baseline:auto behavior that applies by default. Please correct me if I'm wrong.)

[fantasai]

Good point. I checked in an initial fix to this to css-inline; it'll need some more cleanup, though.

[dbaron]

I find it a bit curious that baseline-shift applies to fewer elements than alignment-baseline and dominant-baseline. Though perhaps it makes sense???

[fantasai]

Fixed. File an issue if it shouldn't. :)