  - 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 ?  
const pdfSinglePageViewer = new pdfjsViewer.PDFSinglePageViewer({
  container,
  eventBus,
  linkService: pdfLinkService,
  findController: pdfFindController,
  scriptingManager: pdfScriptingManager,
  enableScripting: true, 
});
pdfLinkService.setViewer(pdfSinglePageViewer);
pdfScriptingManager.setViewer(pdfSinglePageViewer);
eventBus.on("pagesinit", function () {
  
  pdfSinglePageViewer.currentScaleValue = "page-width";
  
  if (SEARCH_FOR) {
    pdfFindController.executeCommand("find", { query: SEARCH_FOR });
  }
});
const loadingTask = pdfjsLib.getDocument({
  url: DEFAULT_URL,
  cMapUrl: CMAP_URL,
  cMapPacked: CMAP_PACKED,
});
loadingTask.promise.then(function (pdfDocument) {
  
  
  pdfSinglePageViewer.setDocument(pdfDocument);
  pdfLinkService.setDocument(pdfDocument, null);
});