nction() {assert_equals(sibling.startTime, 0.0)},
     "After .append, Start time of 'sibling'");
test(function() {assert_equals(child.startTime, 1.0)},
     "After.append, Start time of 'child'");

// Test that setting TimedItem.parent is ignored.
test(function() {
  assert_throws(new TypeError(), function() {
    child.parent = null;
  });
  assert_equals(child.parent, animationSequence);
}, "TimedItem.parent should be read-only");
test(function() {assert_equals(animationSequence.children.length, 2)},
   