[css-inline][css-align] Add issue wrt first/last baseline for vertical-align, and potential impact on css-align properties.

Author: fantasai

css-inline/Overview.bs

@@ -118,6 +118,11 @@ Dominant Baselines: the 'dominant-baseline' property</h3>
 	Issue: Should be text-over and text-under instead of text-top and text-bottom,
 	but maybe it's better not to use those terms for consistency with legacy 'vertical-align'.
 
+	Issue: Add ''first'' and ''last'' values.
+	Note, in this property, these are combinatorial,
+	whereas in the 'align/justify-self/content' properties, it's singular.
+	Do we want to align the syntaxes wrt hyphens vs. spaces or what?
+
 <h3 id="transverse-alignment">
 Transverse Box Alignment: the 'vertical-align' property</h3>