LibWeb: Dispatch animation events before requestAnimationFrame callbacks

Most of the time there won't be any animation frame callbacks, and we
can keep our behavior of dispatching events in the animation timer.

Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp

@@ -253,7 +253,13 @@ void EventLoop::process()
     });
 
     // 10. For each fully active Document in docs, update animations and send events for that Document, passing in now as the timestamp. [WEBANIMATIONS]
-    // Note: This is handled by the document's animation timer
+    // Note: This is handled by the document's animation timer, however, if a document has any requestAnimationFrame callbacks, we need
+    //       to dispatch events before that happens below. Not dispatching here would be observable.
+    for_each_fully_active_document_in_docs([&](DOM::Document& document) {
+        if (document.window()->animation_frame_callback_driver().has_callbacks()) {
+            document.update_animations_and_send_events(document.window()->performance()->now());
+        }
+    });
 
     // FIXME:     11. For each fully active Document in docs, run the fullscreen steps for that Document, passing in now as the timestamp. [FULLSCREEN]