[css-position-4] Add "afterRemoval" steps to top layer removal algorithms

Author: keithamus

css-position-4/Overview.bs

@@ -316,7 +316,7 @@ Top Layer Manipulation {#top-manip}
 
 <div algorithm>
 	To <dfn export lt="request an element to be removed from the top layer | request removal from the top layer">request an element to be removed from the top layer</dfn>,
-	given an {{Element}} |el|:
+	given an {{Element}} |el| and an optional ist of steps |afterRemoval|:
 
 	1. Let |doc| be |el|'s [=Node/node document=].
 
@@ -327,12 +327,12 @@ Top Layer Manipulation {#top-manip}
 
 	3. Remove the UA !important ''overlay: auto'' rule targeting |el|.
 
-	4. [=set/Append=] |el| to |doc|'s [=pending top layer removals=].
+	4. [=set/Append=] (|el|, |afterRemoval|) to |doc|'s [=pending top layer removals=].
 </div>
 
 <div algorithm>
 	To <dfn export lt="remove an element from the top layer immediately | remove from the top layer immediately">remove an element from the top layer immediately</dfn>,
-	given an {{Element}} |el|:
+	given an {{Element}} |el| and an optional list of steps |afterRemoval|:
 
 	1. Let |doc| be |el|'s [=Node/node document=].
 
@@ -341,6 +341,8 @@ Top Layer Manipulation {#top-manip}
 	3. Remove the UA !important ''overlay: auto'' rule targeting |el|,
 		if it exists.
 
+	4. Run |afterRemoval|.
+
 	Note: This algorithm is only intended to be used in special cases
 	where removing something from the top layer immediately
 	(bypassing things like an 'overlay' transition)
@@ -353,10 +355,13 @@ Top Layer Manipulation {#top-manip}
 	To <dfn export>process top layer removals</dfn>,
 	given a {{Document}} |doc|:
 
-	1. For each element |el| in |doc|'s [=pending top layer removals=]:
-		if |el|&apos;s computed value of 'overlay' is ''none'',
-		or |el| is [=not rendered=],
-		[=remove from the top layer immediately=] |el|.
+	1. For each (element |el| and steps |afterRemoval|) in |doc|'s
+		[=pending top layer removals=]: if |el|&apos;s computed value of
+		'overlay' is ''none'', or |el| is [=not rendered=]:
+
+		1. [=remove from the top layer immediately=] |el|.
+
+		2. Run |afterRemoval|.
 
 	Note: This is intended to be called during the "Update the Rendering" step
 	of HTML's rendering algorithm.