[css-contain] ''content'' and ''strict'' compute into the other values

Closes w3c#5511

Author: frivoal

css-contain-1/Overview.bs

@@ -82,7 +82,7 @@ Strong Containment: the 'contain' property</h2>
 		Initial: none
 		Inherited: no
 		Applies to: See <a href="#contain-applies">below</a>
-		Computed value: specified keyword(s)
+		Computed value: specified keyword(s), except ''strict'' and ''content'' (see prose)
 		Animation type: not animatable
 	</pre>
 
@@ -119,8 +119,8 @@ Strong Containment: the 'contain' property</h2>
 
 		<dt><dfn>strict</dfn>
 		<dd>
-			This value turns on all forms of <a>containment</a> for the element.
-			In other words, it behaves the same as ''contain: size layout paint;''.
+			This value computes to ''size layout paint'',
+			and thus turns on all forms of <a>containment</a> for the element.
 
 			<wpt>
 				contain-strict-001.html
@@ -130,8 +130,8 @@ Strong Containment: the 'contain' property</h2>
 
 		<dt><dfn>content</dfn>
 		<dd>
-			This value turns on all forms of <a>containment</a> <em>except</em> <a>size containment</a> for the element.
-			In other words, it behaves the same as ''contain: layout paint;''.
+			This value computes to ''layout paint'',
+			and thus turns on all forms of <a>containment</a> <em>except</em> <a>size containment</a> for the element.
 
 			<wpt>
 				contain-content-001.html

css-contain-2/Overview.bs

@@ -98,7 +98,7 @@ Strong Containment: the 'contain' property</h2>
 		Initial: none
 		Inherited: no
 		Applies to: See <a href="#contain-applies">below</a>
-		Computed value: specified keyword(s)
+		Computed value: specified keyword(s), except ''strict'' and ''content'' (see prose)
 		Animation type: not animatable
 	</pre>
 
@@ -135,8 +135,8 @@ Strong Containment: the 'contain' property</h2>
 
 		<dt><dfn>strict</dfn>
 		<dd>
-			This value turns on all forms of <a>containment</a> <em>except</em> <a>style containment</a> for the element.
-			In other words, it behaves the same as ''contain: size layout paint;''.
+			This value computes to ''size layout paint'',
+			and thus turns on all forms of <a>containment</a> <em>except</em> <a>style containment</a> for the element.
 
 			<wpt>
 				contain-strict-001.html
@@ -147,8 +147,8 @@ Strong Containment: the 'contain' property</h2>
 
 		<dt><dfn>content</dfn>
 		<dd>
-			This value turns on all forms of <a>containment</a> <em>except</em> <a>size containment</a> and <a>style containment</a> for the element.
-			In other words, it behaves the same as ''contain: layout paint;''.
+			This value computes to ''layout paint'',
+			and thus turns on all forms of <a>containment</a> <em>except</em> <a>size containment</a> and <a>style containment</a> for the element.
 
 			<wpt>
 				contain-content-001.html