[css-sizing] Per WG resolution, undo the change that restricted some of the sizing keywords to only some of the sizing properties. Fixes #1913.

Author: tabatkins

css-sizing-3/Overview.bs

@@ -273,7 +273,7 @@ New Keywords for 'width' and 'height'</h3>
 
 	<dl dfn-type=value dfn-for="width, min-width, max-width, height, min-height, max-height">
 <!--
-		<dt><dfn for="width, max-width, height, max-height">stretch</dfn>
+		<dt><dfn>stretch</dfn>
 		<dd>
 			If 'align-self' or 'justify-self' (as appropriate to the relevant axis)
 			is defined to apply,
@@ -302,15 +302,15 @@ New Keywords for 'width' and 'height'</h3>
 			use the <a>min-content inline size</a>;
 			otherwise compute to the property’s <a>initial value</a>.
 <!--
-		<dt><dfn for="width, max-width, height, max-height">fit-content</dfn>
+		<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>.
 -->
-		<dt><dfn for="width, max-width, height, max-height">fit-content(<<length-percentage>>)</dfn>
+		<dt><dfn>fit-content(<<length-percentage>>)</dfn>
 		<dd>
 			If specified for the inline axis,
 			use the fit-content formula