Prune commentary and stale Rust port notes

src/default/attr.rs

@@ -18,8 +18,6 @@ impl<T: HasDefaultUiState> FocusHost for T {
         let state = self.default_state_mut();
         let Some(region) = region else { return };
         state.window.set_ime_allowed(true);
-        // Physical, like everything else this backend hands winit --
-        // `default::content_scale`.
         state.window.set_ime_cursor_area(
             PhysicalPosition::<f32>::from(region.top_left.tuple()),
             PhysicalSize::<f32>::from(region.size().tuple()),