crollable should make it capture the correct descendant\
 snap areas' snap points.");

 // Test that attaching a new snap container also properly assigns snap areas.
 test(() => {
  // All containers should capture snap areas.
  middle_scroller.style.setProperty("overflow", "scroll");
  inner_scroller.style.setProperty("overflow", "scroll");

  // Sanity check that the scrollers still snap to the snap areas.
  document_scroller.scrollTo(0, 10);
  inner_scroller.scrollTo(0,10);
  assert_equals(inner_scroller