[css-sizing-3] Don't compute *-content to 'auto' in block axis bc implementors don't like it. Related to #2708.

Author: tabatkins

css-sizing-3/Overview.bs

@@ -411,21 +411,21 @@ Sizing Values: the <<length-percentage>>, ''width/auto'' | ''max-width/none'', '
 		<dd>
 			If specified for the inline axis,
 			use the <a>min-content inline size</a>;
-			otherwise compute to the property’s <a>initial value</a>.
+			otherwise behaves as the property’s <a>initial value</a>.
 
 		<dt><dfn>max-content</dfn>
 		<dd>
 			If specified for the inline axis,
 			use the <a>max-content inline size</a>;
-			otherwise compute to the property’s <a>initial value</a>.
+			otherwise behaves as the property’s <a>initial value</a>.
 <!--
 		<dt><dfn>fit-content</dfn>
 		<dd>
 			If specified for the inline axis,
 			use the <a>fit-content inline size</a>
 			i.e.
 			<code>min(''width/max-content'', max(''width/min-content'', ''width/stretch''))</code>;
-			otherwise compute to the property’s <a>initial value</a>.
+			otherwise behaves as the property’s <a>initial value</a>.
 -->
 		<dt><dfn>fit-content(<<length-percentage>>)</dfn>
 		<dd>
@@ -434,7 +434,7 @@ Sizing Values: the <<length-percentage>>, ''width/auto'' | ''max-width/none'', '
 			with the <a>available space</a> replaced by the specified argument,
 			i.e.
 			<code>min(''width/max-content'', max(''width/min-content'', <<length-percentage>>))</code>;
-			otherwise compute to the property’s <a>initial value</a>.
+			otherwise behaves as the property’s <a>initial value</a>.
 
 			Negative values are invalid.
 	</dl>