LibWeb: Update spec comments for dialog, popover and close watcher

Author: https://github.com/lukewarlow
Commit: 391a08bf17
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3354
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWeb/HTML/HTMLDialogElement.h

@@ -46,6 +46,8 @@ private:
 
     void run_dialog_focusing_steps();
 
+    void set_close_watcher();
+
     String m_return_value;
     bool m_is_modal { false };
     GC::Ptr<CloseWatcher> m_close_watcher;