LibWeb: Use the specification defined types in IntersectionObserverInit

Author: https://github.com/IdanHo
Commit: 6f7cab91a7
Pull-request: https://github.com/SerenityOS/serenity/pull/13424
Reviewed-by: https://github.com/alimpfard ✅

Userland/Libraries/LibWeb/IntersectionObserver/IntersectionObserver.h

@@ -13,9 +13,9 @@
 namespace Web::IntersectionObserver {
 
 struct IntersectionObserverInit {
-    DOM::Node* root { nullptr };
+    Optional<Variant<NonnullRefPtr<DOM::Element>, NonnullRefPtr<DOM::Document>>> root;
     String root_margin { "0px"sv };
-    JS::Value threshold { 0 };
+    Variant<double, Vector<double>> threshold { 0 };
 };
 
 // https://w3c.github.io/IntersectionObserver/#intersection-observer-interface