[css-conditional-5] Add 'none'-keywords to scroll-state() features (w3c#10874)

- Unintentionally left out in the original scroll-state() PR.
- Reference the media queries spec for boolean context evaluation

Author: lilles

css-conditional-5/Overview.bs

@@ -868,6 +868,8 @@ Container Features</h2>
 	A <dfn export>container feature</dfn>
 	queries a specific aspect of a [=query container=].
 
+	[=Container features=] use the same rules as [=media features=] when evaluating
+	in a [=boolean context=].
 
 <h3 id="size-container">
 Size Container Features</h3>
@@ -1127,7 +1129,7 @@ Sticky positioning: the '@container/stuck' feature</h4>
 	<pre class="descdef mq">
 		Name: stuck
 		For: @container
-		Value: top | right | bottom | left | block-start | inline-start | block-end | inline-end
+		Value: none | top | right | bottom | left | block-start | inline-start | block-end | inline-end
 		Type: discrete
 	</pre>
 
@@ -1152,10 +1154,10 @@ Sticky positioning: the '@container/stuck' feature</h4>
 		</pre>
 	</div>
 
-	In the boolean context, the query matches if visual shift is applied in any
-	direction.
-
 	<dl dfn-type=value dfn-for="@container/stuck">
+		<dt><dfn>none</dfn>
+		<dd>
+			The ''position/sticky'' container is not shifted in any direction.
 		<dt><dfn>top</dfn>
 		<dd>
 			The ''position/sticky'' container is shifted to stay inside the top edge.
@@ -1188,27 +1190,29 @@ Scroll snapping: the '@container/snapped' feature</h4>
 	<pre class="descdef mq">
 		Name: snapped
 		For: @container
-		Value: x | y | block | inline
+		Value: none | x | y | block | inline
 		Type: discrete
 	</pre>
 
 	The '@container/snapped' [=container feature=] queries whether a [=snap target=]
-	is snapped to its [=snap container=] in the given axis. It matches in the boolean
-	context if it is snapped in at least one of the directions.
+	is snapped to its [=snap container=] in the given axis.
 
 	<dl dfn-type=value dfn-for="@container/snapped">
+		<dt><dfn>none</dfn>
+		<dd>
+			The [=query container=] is not a [=snap target=].
 		<dt><dfn>x</dfn>
 		<dd>
 			'@container/snapped' [=container feature=] matches ''x''
-			if the [=query container=] is a horizontal [=snap target=] for its [=scroll container=]
+			if the [=query container=] is a horizontal [=snap target=] for its [=scroll container=].
 		<dt><dfn>y</dfn>
 		<dd>
 			'@container/snapped' [=container feature=] matches ''y''
-			if the [=query container=] is a vertical [=snap target=] for its [=scroll container=]
+			if the [=query container=] is a vertical [=snap target=] for its [=scroll container=].
 		<dt><dfn>block</dfn>
 		<dd>
 			'@container/snapped' [=container feature=] matches ''block''
-			if the [=query container=] is a [=snap target=] for its [=scroll container=]
+			if the [=query container=] is a [=snap target=] for its [=scroll container=].
 			in the block direction of the [=snap container=].
 		<dt><dfn>inline</dfn>
 		<dd>
@@ -1223,7 +1227,7 @@ Overflowing: the '@container/overflowing' feature</h4>
 	<pre class="descdef mq">
 		Name: overflowing
 		For: @container
-		Value: top | right | bottom | left | block-start | inline-start | block-end | inline-end
+		Value: none | top | right | bottom | left | block-start | inline-start | block-end | inline-end
 		Type: discrete
 	</pre>
 
@@ -1237,9 +1241,10 @@ Overflowing: the '@container/overflowing' feature</h4>
 	the [=query container=]. None of the values match if the container is not a
 	[=scroll container=].
 
-	In the boolean context, the query matches if any of the values match.
-
 	<dl dfn-type=value dfn-for="@container/overflowing">
+		<dt><dfn>none</dfn>
+		<dd>
+			The [=scroll container=] does not have [=scrollable overflow=] in any direction.
 		<dt><dfn>top</dfn>
 		<dd>
 			The [=scroll container=] has [=scrollable overflow=] past the top edge.