Settle dirty layout from the leaves upward

tests/retained.rs

@@ -131,34 +131,6 @@ fn a_repaint_that_keeps_its_size_does_not_relay_out() {
     assert_eq!(draws.get(), settled + 1);
 }
 
-#[test]
-fn scrolling_reuses_the_clean_contents_size() {
-    let mut h = Harness::new((400, 200));
-    let (inner, draws) = counted(&mut h, Size::from((400, 600)), OnResize::Translate);
-    let scroll = Scroll::new(inner.add_strong(&mut h.rsc), Axis::Y).add(&mut h.rsc);
-    h.set_root(scroll);
-    let settled = draws.get();
-
-    h.rsc[scroll].scroll(40.0);
-    h.frame();
-
-    assert_eq!(draws.get(), settled);
-    assert_corners!(h, inner, (0, -360), (400, 240));
-}
-
-#[test]
-fn scrolling_remeasures_changed_contents() {
-    let mut h = Harness::new((400, 200));
-    let (inner, _) = counted(&mut h, Size::from((400, 600)), OnResize::Translate);
-    let scroll = Scroll::new(inner.add_strong(&mut h.rsc), Axis::Y).add(&mut h.rsc);
-    h.set_root(scroll);
-
-    h.rsc[inner].size = Size::from((400, 800));
-    h.frame();
-
-    assert_corners!(h, inner, (0, -600), (400, 200));
-}
-
 #[test]
 fn a_placed_child_survives_the_next_frame() {
     let mut h = Harness::new((400, 200));