Update interfaces/wai-aria.idl (#21735)

Source: https://github.com/tidoust/reffy-reports/blob/331b4f2/ed/idl/wai-aria.idl
Build: https://travis-ci.org/tidoust/reffy-reports/builds/649059932
diff --git a/interfaces/wai-aria.idl b/interfaces/wai-aria.idl
index f9406b3..845e2ef 100644
--- a/interfaces/wai-aria.idl
+++ b/interfaces/wai-aria.idl
@@ -22,7 +22,7 @@
   attribute DOMString? ariaCurrent;
   attribute FrozenArray<Element>? ariaDescribedByElements;
   attribute DOMString? ariaDescription;
-  attribute Element? ariaDetailsElement;
+  attribute FrozenArray<Element>? ariaDetailsElements;
   attribute DOMString? ariaDisabled;
   attribute Element? ariaErrorMessageElement;
   attribute DOMString? ariaExpanded;