setTextMapping(textDivs) {
    this.#textChildren = textDivs;
  }
This class aims to provide some methods:
 - to reorder elements in the DOM with respect to the visual order;
 - to create a link, using aria-owns, between spans in the textLayer and
   annotations in the annotationLayer. The goal is to help to know
   where the annotations are in the text flow.