Measure container children without intermediate placement

src/widget/position/scroll.rs

@@ -17,10 +17,7 @@ impl Widget for Scroll {
         let whole = UiRegion::FULL;
         let own = painter.placement();
         let answer_len =
-            match painter.known_len(&self.inner, self.axis, whole, [Some(own.x), Some(own.y)]) {
-                Some(len) => len,
-                None => painter.widget(&self.inner).size().axis(self.axis),
-            };
+            painter.measure_len(&self.inner, self.axis, whole, [Some(own.x), Some(own.y)]);
         let content = answer_len.apply_leftover();
         self.container_len = container_len;
         self.content_len = content.to_px(container_len);

src/widget/position/span.rs

@@ -37,10 +37,7 @@ impl Widget for Span {
             // from the cursor, because a text has to wrap at the width
             // actually there.
             let room = axis.pair(Some(along(cursor, far)), None);
-            let len = match painter.known_len(child, axis, region, room) {
-                Some(len) => len,
-                None => painter.widget_at(child, region, room).len(axis),
-            };
+            let len = painter.measure_len(child, axis, region, room);
             cursor.px += len.px + self.gap;
             cursor.rel += len.rel;
             lens.push(len);