[css-display] Switch table cells and captions to have a 'flow' inner type. Lots of things end up being flow-roots as a result of context (flex items, grid items, absposes, blocks with overflow!=visible, the root element, it's probably simpler just to let those rules take effect rather than hard-coding it in the values.

Author: fantasai

css-display/Overview.bs

@@ -385,7 +385,7 @@ Layout-Internal Display Types: the ''table-*'' and ''ruby-*'' keywords</h3>
 			The element is an <dfn dfn>internal table element</dfn>,
 			and participates in a table layout context. [[!CSS21]]
 
-			''table-cell'' and ''table-caption'' have a ''flow-root'' <a>inner display type</a>.
+			''table-cell'' and ''table-caption'' have a ''flow'' <a>inner display type</a>.
 
 		<dt><dfn>ruby-base</dfn>, <dfn>ruby-text</dfn>, <dfn>ruby-base-container</dfn>, <dfn>ruby-text-container</dfn>
 		<dd>