LibWeb: Unify check_validity for form associated elements

Author: https://github.com/tete17
Commit: af88a43e9a
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6024
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWeb/HTML/HTMLInputElement.h

@@ -160,7 +160,6 @@ public:
     WebIDL::ExceptionOr<void> step_down(WebIDL::Long n = 1);
 
     bool will_validate();
-    WebIDL::ExceptionOr<bool> check_validity();
 
     WebIDL::ExceptionOr<void> show_picker();