[css-values] A few missed calc()-serialization fork edits.

Author: fantasai

css-values-3/Overview.bs

@@ -1607,22 +1607,6 @@ Computed Value</h4>
 	(e.g. <a href="https://www.w3.org/TR/CSS21/visudet.html#the-height-property">the <css>height</css> property</a>),
 	they apply whenever a ''calc()'' expression contains percentages.
 
-	<div class=note>
-		Note: The serialization rules do not preserve the structure of the computation,
-		so implementations can simplify the expressions
-		further than what is required here
-		when storing the values internally;
-		in particular, all ''calc()'' expressions can be reduced
-		to a sum of a <<number>>, a <<percentage>>, and some <<dimension>>s,
-		eliminating all multiplication or division,
-		and combining terms with identical units.
-
-		At this time, all units can be absolutized
-		to a single unit per type at computed-value time,
-		so at that point the ''calc()'' expression can be reduced
-		to just a <<number>>, a <<percentage>>, and a single absolute <<dimension>> of the appropriate type.
-	</div>
-
 	<div class='example'>
 		For example, 'background-position' has special behavior for percentage values, different from lengths:
 

css-values/Overview.bs

@@ -1693,6 +1693,8 @@ Range Checking</h4>
 <h4 id='calc-serialize'>
 Serialization</h4>
 
+	Issue: This section is still <a href="https://lists.w3.org/Archives/Member/w3c-css-wg/2016AprJun/0239.html">under discussion</a>.
+
 	To serialize a ''calc()'' value:
 
 	1. Simplify the expression by: