[css-values-5] Specify that normal simplification *is* done on the calculation (and basis if needed), same as math functions.

Author: tabatkins

css-values-5/Overview.bs

@@ -3741,10 +3741,10 @@ calc-size/animation/interpolate-size-width-interpolation.html
 
 	Whether two ''calc-size()'' functions can be interpolated
 	depends on their [=calc-size basis=] values
-	(after being [=calc-size()/simplified for interpolation=]):
+	(after being [=calc-size()/prepared for interpolation=]):
 
 	<dl class=switch>
-		: If either function returned failure from being [=calc-size()/simplified for interpolation=]
+		: If either function returned failure from being [=calc-size()/prepared for interpolation=]
 		:: The values cannot be interpolated.
 
 		: If they are identical
@@ -3823,18 +3823,22 @@ calc-size/animation/interpolate-size-width-interpolation.html
 <h4 id=simplifying-calc-size>
 Simplifying ''calc-size()''</h4>
 
+	Identically to [=math functions=],
+	the [=calc-size calculation=]
+	(and [=calc-size basis=], if it's a <<calc-sum>>)
+	of a ''calc-size()'' function
+	is [=simplify a calculation tree|simplified=]
+	at [=specified value=] and [=computed value=] time.
+
 	Before [=interpolation=],
-	''calc-size()'' functions are [=calc-size()/simplified for interpolation=]
+	''calc-size()'' functions are [=calc-size()/prepared for interpolation=]
 	so their [=calc-size basises=] can be compared,
 	and their [=calc-size calculations=] can be interpolated properly.
-
-	Note: Unlike [=math functions=],
-	this simplification is <em>not</em> done at other times.
-	The simplification can fail due to substitution exploding,
-	similar to [[#long-substitution]].
+	This is a more involved process than [=simplifying a calculation tree=],
+	and can potentially fail.
 
 	<div algorithm>
-		To <dfn for=calc-size()>simplify for interpolation</dfn>
+		To <dfn for=calc-size()>prepare for interpolation</dfn>
 		a ''calc-size()'' function:
 
 		<ol>