LibWeb: Fix a LibJSGCVerifier warning in DOM::Text

Author: https://github.com/mattco98
Commit: 7001e0a428
Pull-request: https://github.com/SerenityOS/serenity/pull/23861
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/DOM/Text.cpp

@@ -35,8 +35,7 @@ void Text::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
     SlottableMixin::visit_edges(visitor);
-
-    visitor.visit(dynamic_cast<JS::Cell*>(m_owner.ptr()));
+    visitor.visit(m_owner);
 }
 
 // https://dom.spec.whatwg.org/#dom-text-text
@@ -47,6 +46,15 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Text>> Text::construct_impl(JS::Realm& real
     return realm.heap().allocate<Text>(realm, window.associated_document(), data);
 }
 
+EditableTextNodeOwner* Text::editable_text_node_owner()
+{
+    if (!m_owner)
+        return nullptr;
+    EditableTextNodeOwner* owner = dynamic_cast<EditableTextNodeOwner*>(m_owner.ptr());
+    VERIFY(owner);
+    return owner;
+}
+
 // https://dom.spec.whatwg.org/#dom-text-splittext
 // https://dom.spec.whatwg.org/#concept-text-split
 WebIDL::ExceptionOr<JS::NonnullGCPtr<Text>> Text::split_text(size_t offset)