Group goes outside window client area when using bottom-up layout

[zdimension]

Describe the bug Group frame goes outside the window, only if the layout inside is bottom_up.

To Reproduce Steps to reproduce the behavior:

egui::Window::new("window")
    .resizable(false)
    .default_size(egui::Vec2::ZERO)
    .show(ctx, |ui| {
        ui.group(|ui| {
            ui.with_layout(egui::Layout::bottom_up(emath::Align::Min), |ui| {
                ui.add(egui::Label::new("Label A"));
                ui.add(egui::Label::new("Label B"));
            });
        });
    });

Desktop (please complete the following information):

• OS: Windows 10, NVIDIA GeForce GTX 1060

Additional context

• egui 0.20.1, bug present on master as of 34f587d