[selectors-4] Affirmately state where whitespace is forbidden, rather than saying it's forbidden everywhere and then listing exceptions. More correctness; easier to read.

Author: tabatkins

selectors-4/Overview.bs

@@ -3452,15 +3452,17 @@ Grammar</h2>
 	In interpreting the above grammar,
 	the following rules apply:
 
-	* White space is forbidden between tokens except:
-		* Around commas (denoted with the <a data-link-type="grammar">#</a> multiplier)
-		* Around or in place of a <<combinator>>
-		* Between the parentheses and argument of
-			a functional <<pseudo-class-selector>> or <<pseudo-element-selector>>.
-		* Between any of the tokens of an <<attribute-selector>>.
-		* When parsing the argument of any functional notation,
-			whitespace is interpreted as normal for that production
-			(unless otherwise specified, allowed between any pair of tokens).
+	* White space is forbidden:
+		* Between any of the top-level components of a <<compound-selector>>
+			(that is, forbidden between the <<type-selector>> and <<subclass-selector>>,
+			or between the <<subclass-selector>> and <<pseudo-element-selector>>,
+			etc).
+		* Between <em>any</em> of the components of a <<type-selector>>
+			or a <<class-selector>>.
+		* Between the ':'s, or between the ':' and <<ident-token>> or <<function-token>>,
+			of a <<pseudo-element-selector>> or a <<pseudo-class-selector>>.
+		* Between <em>any</em> of the components of a <<wq-name>>.
+		* Between the components of an <<attr-matcher>>.
 	* The four <a href="https://www.w3.org/TR/CSS2/selectors.html#pseudo-element-selectors">Level 2</a> <a>pseudo-elements</a>
 		(''::before'', ''::after'', ''::first-line'', and ''::first-letter'')
 		may, for legacy reasons,