On Linux, an element whose LayoutTransform isn't the identity, and which stretches to fill its
slot, is measured and arranged at the slot's own size, and the transform is then applied to that.

Elements with a fixed size, or not stretched, are laid out correctly, as are stretched elements in
an unbounded slot (a Canvas) and an identity transform.

What it breaks: Toolkit's LayoutScaler gives its stretched child a ScaleTransform, so on
Linux the content is scaled twice. The SDK's own Inventory sample (MainPage.xaml: a LayoutScaler
with the default 1920 × 1080 reference) is drawn at 0.6 of a 1152 × 648 window, centred on black,
where Windows fills the window with the same XAML.

The issue can be clearly reproduced with the Gui.XamlPlayer and Inventory sample on Linux.