Remove 'enforceCSSGrammar'; that'll be done by constructable stylesheets. Add an issue about atRules.

Author: tabatkins

css-parser-api/Overview.bs

@@ -53,7 +53,8 @@ partial interface CSS {
 
 dictionary CSSParserOptions {
 	object atRules;
-	boolean enforceCSSGrammar = false;
+	/* dict of at-rule name => at-rule type
+	   (contains decls or contains qualified rules) */
 };
 </pre>
 
@@ -74,6 +75,12 @@ Maybe add an option to preserve comments?
 If so, they can appear *anywhere*,
 in any API that returns a sequence.
 
+Issue: What do we do if an unknown at-rule
+(not appearing in the {{atRules}} option)
+shows up in the results?
+Default to decls or rules?
+Or treat it more simply as just a token sequence?
+
 Parser Values {#parser-values}
 ==============================