  - Open https://mozilla.github.io/pdf.js/web/viewer.html
  - Open a pdf with some XFA (for example the on in https://github.com/mozilla/pdf.js/issues/13679#issue-937616350)

The pdf is not correctly displayed because `enableXfa` is false.

@Snuffleupagus, the pref is set to true in Firefox nightly, is there anything blocking setting it to true in the web viewer ?  
if (this.textLayerRenderTask) {
      this.textLayerRenderTask.cancel();
      this.textLayerRenderTask = null;
    }
    this.highlighter?.disable();
  }
  setTextContentStream(readableStream) {
    this.cancel();
    this.textContentStream = readableStream;
  }
  setTextContent(textContent) {
    this.cancel();
    this.textContent = textContent;
  }
  /**
   * Improves text selection by adding an additional div where the mouse was
   * clicked. This reduces flickering of the content if the mouse is slowly
   * dragged up or down.
   *
   * @private
   */
  _bindMouse() {
    const div = this.textLayerDiv;
    let expandDivsTimer = null;
    div.addEventListener("mousedown", evt => {
      if (this.enhanceTextSelection && this.textLayerRenderTask) {
        this.textLayerRenderTask.expandTextDivs(true);
        if (
          (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) &&
          expandDivsTimer