fix(template-heading-level): exclude abstract roles from VALID_ROLE_TOKENS

Author: johanrd

lib/rules/template-heading-level.js

@@ -13,8 +13,12 @@ const HEADING_RE = /^h([1-6])$/;
 
 // Valid ARIA role tokens — used to find the first recognised token in a
 // space-separated role-fallback list (WAI-ARIA §4.1). `presentation`/`none`
-// are included in aria-query's role map.
-const VALID_ROLE_TOKENS = new Set(ariaRoles.keys());
+// are included in aria-query's role map. Abstract roles (e.g. `widget`,
+// `structure`, `landmark`) are excluded: WAI-ARIA forbids authors from using
+// abstract roles as `role` attribute values.
+const VALID_ROLE_TOKENS = new Set(
+  [...ariaRoles.keys()].filter((name) => !ariaRoles.get(name).abstract)
+);
 
 function extractLevel(tag) {
   const match = HEADING_RE.exec(tag);