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.
const pendingProps = portal.children !== null ? portal.children : [];
  const fiber = createFiber(HostPortal, pendingProps, portal.key, mode);
  fiber.expirationTime = expirationTime;
  fiber.stateNode = {
    containerInfo: portal.containerInfo,
    pendingChildren: null, // 
    implementation: portal.implementation,
  };
  return fiber;
}
// Used for stashing WIP properties to replay failed work in DEV.
export function assignFiberPropertiesInDEV(
  target: Fiber | null,
  source: Fiber,
): Fiber {
  if (target === null) {
    // 
    // 
    target = createFiber(IndeterminateComponent, null, null, NoContext);
  }
  // 
  // 
  // 
  // 
  // 
  target.tag = source.tag;
  target.key = source.key;
  target.type = source.type;
  target.stateNode = source.stateNode;
  target.return = source.return;