`SLINT_DEBUG_PERFORMANCE` overlay not working with Skia

[Enyium]

I'm on Windows 10 using Rust.

With FemtoVG it works, but with Skia setting the env var SLINT_DEBUG_PERFORMANCE=refresh_full_speed,overlay,console before executing cargo run renders no overlay at all. The console prints happen, though (they look a bit different: FemtoVG adds details from last frame: [0 layers created]).

[Simon Hausmann]

I can confirm. This used to work, but that was before the FontMgr changes.