[css-cascade-4][css-scoping-1] Move Shadow DOM cascade definition into css-cascade. w3c#5372

Author: fantasai

css-cascade-4/Overview.bs

@@ -789,6 +789,18 @@ Cascade Order</h3>
 
 			Declarations from <a>origins</a> earlier in this list win over declarations from later <a>origins</a>.
 
+		<dt id='cascade-context'>Context
+		<dd>
+			A document language can provide for blending declarations sourced
+			from different <dfn>encapsulation contexts</dfn>,
+			such as the nested [=tree contexts=] of [=shadow trees=] in the [[!DOM]].
+			When comparing two declarations
+			that are sourced from different [=encapsulation contexts=],
+			then for normal rules
+			the declaration in the outer context wins,
+			and for [=important=] rules
+			the declaration from the inner context wins.
+
 		<dt id='cascade-scope'>Scope
 		<dd>
 			A declaration can be <dfn export>scoped</dfn> to a subtree of the document

css-scoping-1/Overview.bs

@@ -435,20 +435,7 @@ Selecting Slot-Assigned Content: the ''::slotted()'' pseudo-element</h4>
 <h3 id='shadow-cascading'>
 Shadow Trees and the Cascade</h3>
 
-	To address the desired cascading behavior of rules targetting elements in shadow roots,
-	this specification extends the <a href="https://drafts.csswg.org/css-cascade/#cascading">cascade order</a>
-	defined in the Cascade specification. [[!CSS3CASCADE]]
-
-	An additional cascade criteria must be added,
-	between Origin and Scope,
-	called Shadow Tree.
-
-	* When comparing two declarations
-		that have different <a>tree contexts</a>,
-		then for normal rules the declaration earlier in the <a>shadow-including tree order</a> wins,
-		and for important rules the declaration coming later in the <a>shadow-including tree order</a> wins.
-
-		Note: This is the <em>opposite</em> of how scoped styles work.
+	See [[css-cascade-4#cascade-context]].
 
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