[css-sizing-3] Allow intrinsic sizing keywords to mean the corrsponding intrinsic sizes. Default to automatic size in the block axis unless otherwise defined. #3973 #4587

Author: fantasai

css-sizing-3/Overview.bs

@@ -445,20 +445,21 @@ Sizing Values: the <<length-percentage>>, ''width/auto'' | ''max-width/none'', '
 
 		<dt><dfn>min-content</dfn>
 		<dd>
-			If specified for the inline axis,
-			use the <a>min-content inline size</a>;
-			otherwise compute to ''width/auto''.
+			Use the <a>min-content size</a> in the relevant axis;
+			for a box’s [=block size=],
+			unless otherwise specified,
+			this is equivalent to its [=automatic size=].
 
 		<dt><dfn>max-content</dfn>
 		<dd>
-			If specified for the inline axis,
-			use the <a>max-content inline size</a>;
-			otherwise compute to ''width/auto''.
+			Use the <a>min-content size</a> in the relevant axis;
+			for a box’s [=block size=],
+			unless otherwise specified,
+			this is equivalent to its [=automatic size=].
 <!--
 		<dt><dfn>fit-content</dfn>
 		<dd>
-			Use the <a>fit-content inline size</a> or <a>fit-content block size</a>,
-			as appropriate to the writing mode,
+			Use the <a>fit-content size</a> in the relevant axis,
 			i.e.
 			<code>min(''width/max-content'', max(''width/min-content'', ''width/stretch''))</code>.
 -->