function enqueueMove(parentID, fromIndex, toIndex) {
  // NOTE: Null values reduce hidden classes.
  updateQueue.push({
    parentID: parentID,
    parentNode: null,
    type: ReactMultiChildUpdateTypes.MOVE_EXISTING,
    markupIndex: null,
    content: null,
    fromIndex: fromIndex,
    toIndex: toIndex
  });
}
Enqueues moving an existing element to another index.

@param {string} parentID ID of the parent component.
@param {number} fromIndex Source index of the existing element.
@param {number} toIndex Destination index of the element.
@private