LibWeb: Stub out a few form validation and selection methods

Author: https://github.com/elisee
Commit: 38a3e28799
Pull-request: https://github.com/SerenityOS/serenity/pull/17920
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/HTML/HTMLFormElement.idl

@@ -12,6 +12,8 @@ interface HTMLFormElement : HTMLElement {
 
     undefined submit();
     [CEReactions] undefined reset();
+    boolean checkValidity();
+    boolean reportValidity();
 
     // FIXME: Should be a HTMLFormControlsCollection
     [SameObject] readonly attribute HTMLCollection elements;