Track retained layout validity explicitly

src/widget/position/offset.rs

@@ -10,8 +10,4 @@ impl Widget for Offset {
         let region = UiRegion::FULL.offset(self.amt);
         painter.widget_within(&self.inner, region).size()
     }
-
-    fn on_resize(&self, _: Axis) -> OnResize {
-        OnResize::Scale
-    }
 }