LibWeb/XHR: Add missing spec comment for step 12 in XHR::send()

Author: https://github.com/kennethmyhra
Commit: 5d94119f4c
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5943
Reviewed-by: https://github.com/gmta ✅
Reviewed-by: https://github.com/trflynn89 ✅

Libraries/LibWeb/XHR/XMLHttpRequest.cpp

@@ -883,7 +883,9 @@ WebIDL::ExceptionOr<void> XMLHttpRequest::send(Optional<DocumentOrXMLHttpRequest
 
             timer->start();
         }
-    } else {
+    }
+    // 12. Otherwise, if this’s synchronous flag is set:
+    else {
         // 1. Let processedResponse be false.
         IGNORE_USE_IN_ESCAPING_LAMBDA bool processed_response = false;