IFrame in Dialog creates two requests to source

[stefan-dorner]

Description of the bug

When I create an IFrame inside a Dialog, the IFrame's source is requested twice. If I place the IFrame inside a Span without a dialog, the request is only created once.

Expected behavior

Opening an IFrame in a Dialog should create just one request to the IFrame source.

Minimal reproducible example

add(new Button("Open IFrame", e ->  {
    Dialog dialog = new Dialog();
    dialog.add(new IFrame("https://www.example.com"));
    dialog.open();
}));

Versions

• Vaadin / Flow version: 24.3.5