I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

const numLabels = labels.length;
    if (numLabels !== this.pagesCount) {
      console.error(
        "The number of Page Labels does not match the number of pages in the document."
      );
      return;
    }
    let i = 0;
    
    while (i < numLabels && labels[i] === (i + 1).toString()) {
      i++;
    }
    if (i === numLabels) {
      return;
    }
    const { pdfViewer, pdfThumbnailViewer, toolbar } = this;
    pdfViewer.setPageLabels(labels);
    pdfThumbnailViewer.setPageLabels(labels);
    
    
    toolbar.setPagesCount(numLabels, true);
    toolbar.setPageNumber(
      pdfViewer.currentPageNumber,
      pdfViewer.currentPageLabel
    );
  },
  /**
   * @private
   */
  _initializePdfHistory({ fingerprint, viewOnLoad, initialDest = null }) {