LibWeb: Implement dialog.requestClose()

Author: https://github.com/lukewarlow
Commit: dd37d1c536
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3280
Reviewed-by: https://github.com/ADKaster ✅

Libraries/LibWeb/HTML/HTMLDialogElement.idl

@@ -12,6 +12,6 @@ interface HTMLDialogElement : HTMLElement {
     [CEReactions] undefined show();
     [CEReactions] undefined showModal();
     [CEReactions] undefined close(optional DOMString returnValue);
-    [FIXME, CEReactions] undefined requestClose(optional DOMString returnValue);
+    [CEReactions] undefined requestClose(optional DOMString returnValue);
 
 };