[css-values-4] A small fix and some tweaks to calc serialization (w3c#11782)

* [css-values-4] Remove outdated link to calc-serialization issue

See w3c#6506 (comment)

* [css-values-4] Close parentheses in math-function serialization step 2.4

* [css-values-4] Number per-type steps of calculation tree serialization

---------

Co-authored-by: Tab Atkins Jr. <jackalmage@gmail.com>

Author: AtkinsSJ

css-values-4/Overview.bs

@@ -5066,8 +5066,6 @@ Range Checking</h3>
 <h3 id='calc-serialize'>
 Serialization</h3>
 
-	Issue: This section is still <a href="https://lists.w3.org/Archives/Member/w3c-css-wg/2016AprJun/0239.html">under discussion</a>.
-
 	<div algorithm>
 		To <dfn export>serialize a math function</dfn> |fn|:
 
@@ -5094,7 +5092,7 @@ Serialization</h3>
 				with a value of 1.
 				Serialize this numeric value
 				and append it to |s|.
-			3. Return |s|.
+			4. Append ")" to |s|, then return it.
 
 		3. If the [=calculation tree’s=] root node is a numeric value,
 			or a [=calc-operator node=],
@@ -5141,78 +5139,82 @@ Serialization</h3>
 			treating the node's children as the function's comma-separated [=calculation=] arguments,
 			and return the result.
 
-		4. If |root| is a Negate node,
-			let |s| be a [=string=]
-			initially containing "(-1 * ".
+		4. If |root| is a Negate node:
+			
+			1. Let |s| be a [=string=]
+				initially containing "(-1 * ".
+
+			2. [=serialize a calculation tree|Serialize=] |root|'s child,
+				and append it to |s|.
 
-			[=serialize a calculation tree|Serialize=] |root|'s child,
-			and append it to |s|.
+			3. Append ")" to |s|,
+				then return it.
 
-			Append ")" to |s|,
-			then return it.
+		5. If |root| is an Invert node:
 
-		5. If |root| is an Invert node,
-			let |s| be a [=string=]
+			1. Let |s| be a [=string=]
 			initially containing "(1 / ".
 
-			[=serialize a calculation tree|Serialize=] |root|'s child,
-			and append it to |s|.
+			2. [=serialize a calculation tree|Serialize=] |root|'s child,
+				and append it to |s|.
+
+			3. Append ")" to |s|,
+				then return it.
+
+		6. If |root| is a Sum node:
 
-			Append ")" to |s|,
-			then return it.
+			1. Let |s| be a [=string=]
+				initially containing "(".
 
-		6. If |root| is a Sum node,
-			let |s| be a [=string=]
-			initially containing "(".
+			2. [=sort a calculation's children|Sort root's children=].
 
-			[=sort a calculation's children|Sort root's children=].
+			3. [=serialize a calculation tree|Serialize=] |root|'s first child,
+				and append it to |s|.
 
-			[=serialize a calculation tree|Serialize=] |root|'s first child,
-			and append it to |s|.
+			4. [=list/For each=] |child| of |root| beyond the first:
 
-			[=list/For each=] |child| of |root| beyond the first:
+				1. If |child| is a Negate node,
+					append " - " to |s|,
+					then [=serialize a calculation tree|serialize=] the Negate's child
+					and append the result to |s|.
 
-			1. If |child| is a Negate node,
-				append " - " to |s|,
-				then [=serialize a calculation tree|serialize=] the Negate's child
-				and append the result to |s|.
+				2. If |child| is a negative numeric value,
+					append " - " to |s|,
+					then serialize the negation of |child| as normal
+					and append the result to |s|.
 
-			3. If |child| is a negative numeric value,
-				append " - " to |s|,
-				then serialize the negation of |child| as normal
-				and append the result to |s|.
+				3. Otherwise,
+					append " + " to |s|,
+					then [=serialize a calculation tree|serialize=] |child|
+					and append the result to |s|.
 
-			2. Otherwise,
-				append " + " to |s|,
-				then [=serialize a calculation tree|serialize=] |child|
-				and append the result to |s|.
+			5. Append ")" to |s|
+				and return it.
 
-			Finally, append ")" to |s|
-			and return it.
+		7. If |root| is a Product node:
 
-		7. If |root| is a Product node,
-			let |s| be a [=string=]
-			initially containing "(".
+			1. Let |s| be a [=string=]
+				initially containing "(".
 
-			[=sort a calculation's children|Sort root's children=].
+			2. [=sort a calculation's children|Sort root's children=].
 
-			[=serialize a calculation tree|Serialize=] |root|'s first child,
-			and append it to |s|.
+			3. [=serialize a calculation tree|Serialize=] |root|'s first child,
+				and append it to |s|.
 
-			[=list/For each=] |child| of |root| beyond the first:
+			4. [=list/For each=] |child| of |root| beyond the first:
 
-			1. If |child| is an Invert node,
-				append " / " to |s|,
-				then [=serialize a calculation tree|serialize=] the Invert's child
-				and append the result to |s|.
+				1. If |child| is an Invert node,
+					append " / " to |s|,
+					then [=serialize a calculation tree|serialize=] the Invert's child
+					and append the result to |s|.
 
-			2. Otherwise,
-				append " * " to |s|,
-				then [=serialize a calculation tree|serialize=] |child|
-				and append the result to |s|.
+				2. Otherwise,
+					append " * " to |s|,
+					then [=serialize a calculation tree|serialize=] |child|
+					and append the result to |s|.
 
-			Finally, append ")" to |s|
-			and return it.
+			5. Append ")" to |s|
+				and return it.
 	</div>
 
 	<div algorithm>