Function markHiddenUpdate

packages/react-reconciler/src/ReactFiberLane.js:1070–1084

(
  root: FiberRoot,
  update: ConcurrentUpdate,
  lane: Lane,
)

}

export function markHiddenUpdate(
  root: FiberRoot,
  update: ConcurrentUpdate,
  lane: Lane,
) {
  const index = laneToIndex(lane);
  const hiddenUpdates = root.hiddenUpdates;
  const hiddenUpdatesForLane = hiddenUpdates[index];
  if (hiddenUpdatesForLane === null) {
    hiddenUpdates[index] = [update];
  } else {
    hiddenUpdatesForLane.push(update);
  }
  update.lane = lane | OffscreenLane;
}

export function getBumpedLaneForHydration(
  root: FiberRoot,