[selectors-4] Update to ::slotted w3c#7474

Author: fantasai

selectors-4/Overview.bs

@@ -872,8 +872,8 @@ Internal Structure</h4>
 
 	<div class="example">
 		For example, ''::first-letter + span'' and ''::first-letter em'' are invalid selectors.
-		However, since ''::shadow'' is defined to have internal structure,
-		''::shadow > p'' is a valid selector.
+		However, since ''::slotted'' is defined to have internal structure,
+		''::slotted > p'' is a valid selector.
 	</div>
 
 	Note: A future specification may expand the capabilities of existing pseudo-elements,
@@ -885,7 +885,7 @@ Internal Structure</h4>
 
 	<div class='example'>
 		For example,
-		the ''::content'' pseudo-element treats elements distributed to it as its children.
+		the ''::slotted'' pseudo-element treats elements distributed to it as its children.
 		This means that, given the following fragment:
 
 		<pre>
@@ -897,7 +897,7 @@ Internal Structure</h4>
 		&lt;/div>
 		</pre>
 
-		the selectors ''div > span'' and ''div::shadow ::content > span'' select the same element via different paths.
+		the selectors ''div > span'' and ''div::shadow ::slotted > span'' select the same element via different paths.
 
 		However, when rendered,
 		the <code>&lt;span></code> element generates boxes as if it were the child of the <code>&lt;content></code> element,