[css-syntax] Make <CDO> and <CDC> not special in "Parse a rule".

This is consistent with "Parse a list of rules".

Author: SimonSapin

css-syntax/Overview.html

@@ -3063,8 +3063,7 @@ <h4 id=parse-a-rule><span class=secno>5.3.3. </span> <dfn
         non-〈whitespace〉 is reached.
 
        <li> If the <a href="#current-input-token"><i>current input
-        token</i></a> is a 〈CDO〉, 〈CDC〉, or 〈EOF〉, return a
-        syntax error.
+        token</i></a> is a 〈EOF〉, return a syntax error.
         <p> Otherwise, if the <a href="#current-input-token"><i>current input
          token</i></a> is an 〈at-keyword〉, <a
          href="#consume-an-at-rule0"><i>consume an at-rule</i></a>.

css-syntax/Overview.src.html

@@ -2013,8 +2013,7 @@ <h4>
 			Consume 〈whitespace〉s from the token stream until a non-〈whitespace〉 is reached.
 
 		<li>
-			If the <i>current input token</i>
-			is a 〈CDO〉, 〈CDC〉, or 〈EOF〉,
+			If the <i>current input token</i> is a 〈EOF〉,
 			return a syntax error.
 
 			<p>