[css-cascade-6] Add CSSScopeRule (w3c#8468)

Author: andruud

css-cascade-6/Overview.bs

@@ -575,6 +575,54 @@ Precedence of Non-CSS Presentational Hints</h3>
 
 	Issue: [[css-cascade-5#layering]]
 
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+
+CSSOM {#cssom}
+==============
+
+
+<h3 id="the-cssscoperule-interface">
+The <code>CSSScopeRule</code> interface</h3>
+
+	The {{CSSScopeRule}} interface represents the ''@scope'' rule:
+
+	<pre class='idl' export>
+	[Exposed=Window]
+	interface CSSScopeRule : CSSGroupingRule {
+	  readonly attribute CSSOMString start;
+	  readonly attribute CSSOMString end;
+	};
+	</pre>
+
+	<dl class='idl-attributes'>
+		<dt><code>start</code> of type <code>CSSOMString</code>
+		<dd>The <code>start</code> attribute must return a value as follows:
+
+			<dl class="switch">
+				<dt data-md>The ''@scope'' rule has an associated <<scope-start>>
+				<dd data-md>The result of serializing that <<scope-start>>.
+				<dt data-md>Otherwise
+				<dd data-md>An empty string.
+			</dl>
+
+		<dt><code>end</code> of type <code>CSSOMString</code>
+		<dd>The <code>end</code> attribute must return a value as follows:
+
+			<dl class="switch">
+				<dt data-md>The ''@scope'' rule has an associated <<scope-end>>
+				<dd data-md>The result of serializing that <<scope-end>>.
+				<dt data-md>Otherwise
+				<dd data-md>An empty string.
+			</dl>
+	</dl>
 
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@@ -597,6 +645,8 @@ Changes since the 21 December 2021 First Public Working Draft</h3>
 	Significant changes since the
 	<a href="https://www.w3.org/TR/2021/WD-css-cascade-6-20211221/">21 December 2021 First Public Working Draft</a> include:
 
+	* Added the {{CSSScopeRule}} interface.
+
 	* Added [=implicit scopes=].
 		(<a href="https://github.com/w3c/csswg-drafts/issues/6606">Issue 6606</a>)