LibWeb: Implement :required/:optional pseudo-classes

Author: https://github.com/Gingeh
Commit: 7acc0f4a42
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4838
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/CSS/StyleInvalidationData.cpp

@@ -141,6 +141,8 @@ static void build_invalidation_sets_for_simple_selector(Selector::SimpleSelector
         case PseudoClass::Link:
         case PseudoClass::AnyLink:
         case PseudoClass::LocalLink:
+        case PseudoClass::Required:
+        case PseudoClass::Optional:
             invalidation_set.set_needs_invalidate_pseudo_class(pseudo_class.type);
             break;
         default: