[css-nesting-1][css-cascade-6] Scoped '&' behaves like :where(:scope) (#12914)

Resolves #9740.

Author: andruud

css-cascade-6/Overview.bs

@@ -314,11 +314,7 @@ Effects of ''@scope''</h4>
 		the ''@scope'' rule’s [=scoping root=],
 		including the [=featureless=] [=shadow host=]
 		when that host is the [=scoping root=].
-		The ''&'' selector is defined to represent
-		the selector representing the [=scoping root=]
-		(the <<scope-start>> selector),
-		or else '':scope'' if no selector was specified.
-
+	* The ''&'' selector is defined to behave as <code>:where(:scope)</code>.
 	* The [=cascade=] prioritizes declarations
 		with a [=scope proximity|more proximate=] [=scoping root=],
 		regardless of specificity or order of appearance
@@ -518,19 +514,11 @@ Scoped Style Rules</h4>
 		}
 		</pre>
 
-		While the '':scope'' or ''&'' selectors
-		can both refer to the [=scoping root=],
-		they have otherwise different meanings in this context:
-
-		: Differences in selector matching
-		:: The '':scope'' selector will only match the [=scoping root=] itself,
-			while the ''&'' selector is able to match any element
-			that is matched by the <<scope-start>> selector list.
-		: Differences in selector specificity
-		:: The '':scope'' selector has a specificity
-			equal to other pseudo-classes,
-			while the ''&'' selector has the specificity
-			equal to the most specific selector in <<scope-start>>.
+		Both the '':scope'' and ''&'' selectors
+		match the [=scope root=],
+		but with different [=specificity=]:
+		'':scope'' has as [=specificity=] of (0,1,0), 
+		whereas ''&'' has a [=specificity=] of 0.
 	</div>
 
 <h4 id="scope-limits">
@@ -773,6 +761,9 @@ Changes since the 21 March 2023 Working Draft</h3>
 	Significant changes since the
 	<a href="https://www.w3.org/TR/2023/WD-css-cascade-6-20230321/">21 March 2023 Working Draft</a> include:
 
+	* Defined ''&'' to behave like <code>:where(:scope)</code>.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/9740">Issue 9740</a>)
+
 	* Allowed [=declarations=] directly within ''@scope''.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/10389">Issue 10389</a>)
 

css-nesting-1/Overview.bs

@@ -763,11 +763,6 @@ Nested ''@scope'' Rules</h4>
 	refers to the elements matched
 	by the nearest ancestor style rule.
 
-	For the purposes of the style rules in its body
-	and its own <<scope-end>> selector,
-	the ''@scope'' rule is treated as an ancestor style rule,
-	matching the elements matched by its <<scope-start>> selector.
-
 	<div class=example>
 		That is, the following code:
 
@@ -787,14 +782,19 @@ Nested ''@scope'' Rules</h4>
 
 		<pre highlight=css>
 		.parent { color: blue; }
-		@scope (.parent > .scope) to (.parent > .scope .limit) {
-			.parent > .scope .content {
+		@scope (.parent > .scope) to (:where(:scope) .limit) {
+			:where(:scope) .content {
 				color: red;
 			}
 		}
 		</pre>
 	</div>
 
+	<div class=note>
+	The ''&'' selector behaves like <code>:where(:scope)</code>
+	in ''@scope'' rules.
+	</div>
+
 <!-- Big Text: mixing
 
 █     █ ████ █     █ ████ █    █▌  ███▌
@@ -1344,6 +1344,10 @@ will collapse into a single rule when serialized and parsed again.
 Significant changes since the
 <a href="https://www.w3.org/TR/2023/WD-css-nesting-1-20230214/">Feb 14, 2023 Working Draft</a>:
 
+* The ''<scope-start>'' selector of a ''@scope'' rule
+	no longer acts as the parent rule for nesting.
+	(<a href="https://github.com/w3c/csswg-drafts/issues/9740">Issue 9740</a>)
+
 * Clarified that the [=nesting selector=] is allowed to match featureless elements.
 
 * Switched ''&div'' back to being invalid;