This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
const root = (workInProgress.stateNode: FiberRoot);
  if (root.pendingContext) {
    pushTopLevelContextObject(
      workInProgress,
      root.pendingContext,
      root.pendingContext !== root.context,
    );
  } else if (root.context) {
    
    pushTopLevelContextObject(workInProgress, root.context, false);
  }
  pushHostContainer(workInProgress, root.containerInfo);
}
function updateHostRoot(current, workInProgress, renderLanes) {
  pushHostRootContext(workInProgress);
  const updateQueue = workInProgress.updateQueue;
  invariant(
    current !== null && updateQueue !== null,
    'If the root does not have an updateQueue, we should have already ' +
      'bailed out. This error is likely caused by a bug in React. Please ' +
      'file an issue.',
  );
  const nextProps = workInProgress.pendingProps;
  const prevState = workInProgress.memoizedState;
  const prevChildren = prevState.element;
  cloneUpdateQueue(current, workInProgress);
  processUpdateQueue(workInProgress, nextProps, null, renderLanes);
  const nextState = workInProgress.memoizedState;
  const root: FiberRoot = workInProgress.stateNode;
  if (enableCache) {