  assert.deepEqual(allInsertionPoints(child), [c1, c2]);
  child.slot = 's3';
  c1.setAttribute('name', 's3');
  c1.slot = 's3';
  c2.setAttribute('name', 's3');
  c2.slot = 's3';
  flush();
  assert.deepEqual(allInsertionPoints(child), [c1, c2, c3]);
  child.slot = '';
  flush();
  assert.deepEqual(allInsertionPoints(child), []);
  child.slot = 's3';
  flush();
  assert.deepEqual(allInsertionPoints(child), [c1, c2, c3]);
  child.slot = '';
  flush();
  assert.deepEqual(allInsertionPoints(child), []);
  chi