Fix overlay clearing regression from #2521 with high-DPIs

Closes #2628

Author: Keavon

editor/src/messages/portfolio/document/overlays/overlays_message_handler.rs

@@ -47,7 +47,7 @@ impl MessageHandler<OverlaysMessage, OverlaysMessageData<'_>> for OverlaysMessag
 
 				let [a, b, c, d, e, f] = DAffine2::from_scale(DVec2::splat(device_pixel_ratio)).to_cols_array();
 				let _ = context.set_transform(a, b, c, d, e, f);
-				context.clear_rect(0., 0., canvas.width().into(), canvas.height().into());
+				context.clear_rect(0., 0., ipp.viewport_bounds.size().x, ipp.viewport_bounds.size().y);
 				let _ = context.reset_transform();
 
 				if visibility_settings.all() {