On Wayland, improve initial user size handling

Keep the user provided size in the original values and convert only
when we're getting a `configure` event. On some compositors will
have a scale available, so it'll work, however with some we'll
still have old 'pick 1` as default.

Also configure_bounds when compositor tells the user to pick the size,
that will ensure that initial `with_inner_size` won't grow beyond the
working area.

Fixes #3187.

src/platform_impl/linux/x11/monitor.rs

@@ -212,7 +212,7 @@ impl XConnection {
             return Ok(MonitorHandle::dummy());
         }
 
-        let default = monitors.get(0).unwrap();
+        let default = monitors.first().unwrap();
 
         let window_rect = match window_rect {
             Some(rect) => rect,