While working on the DevTools profiler, I've noticed that durations are sometimes incorrect. This seems to be vaguely related to high/low priority state updates. Need to track this down more so I'm filing an issue for myself.
element: ReactElement,
  mode: TypeOfMode,
  expirationTime: ExpirationTime,
): Fiber {
  let owner = null;
  if (__DEV__) {
    owner = element._owner;
  }
  let fiber;
  const type = element.type;
  const key = element.key;
  let pendingProps = element.props;
  let fiberTag;
  if (typeof type === 'function') {
    fiberTag = shouldConstruct(type) ? ClassComponent : IndeterminateComponent;
  } else if (typeof type === 'string') {
    fiberTag = HostComponent;
  } else {
    switch (type) {
      case REACT_FRAGMENT_TYPE:
        return createFiberFromFragment(
          pendingProps.children,
          mode,
          expirationTime,