[css-align-3] Use alignment, not dominant, baseline. w3c#7856 w3c#7639

Author: fantasai

css-align-3/Overview.bs

@@ -2206,13 +2206,14 @@ Determining the Baselines of a Box</h2>
 		<dd>
 			The first [=baseline set=] of a <a>multi-column container</a>
 			is the first [=baseline set=] of the [=column=] or [=spanner=]
-			with the highest ([=block-start=]&ndash;most) [=dominant baseline=].
+			with the highest ([=block-start=]&ndash;most) baseline
+			corresponding to the [=multi-column container=]'s [=alignment baseline=].
 			If there is no such line box or child,
 			then the multi-column container has no first [=baseline set=].
 
 			The last [=baseline set=] is analogous,
 			but uses the last [=baseline set=] from the [=column=] or [=spanner=]
-			with the <em>lowest</em> ([=block-end=]&ndash;most) [=dominant baseline=].
+			with the <em>lowest</em> ([=block-end=]&ndash;most) baseline.
 
 		<dt>tables
 		<dd>