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 file = evt.fileInput.files[0];
    if (!viewerCompatibilityParams.disableCreateObjectURL) {
      let url = URL.createObjectURL(file);
      if (file.name) {
        url = { url, originalUrl: file.name };
      }
      PDFViewerApplication.open(url);
    } else {
      PDFViewerApplication.setTitleUsingUrl(file.name);
      
      const fileReader = new FileReader();
      fileReader.onload = function webViewerChangeFileReaderOnload(event) {
        const buffer = event.target.result;
        PDFViewerApplication.open(new Uint8Array(buffer));
      };
      fileReader.readAsArrayBuffer(file);
    }
    
    const appConfig = PDFViewerApplication.appConfig;
    appConfig.toolbar.viewBookmark.hidden = true;
    appConfig.secondaryToolbar.viewBookmarkButton.hidden = true;
    appConfig.toolbar.download.hidden = true;
    appConfig.secondaryToolbar.downloadButton.hidden = true;
  };
  webViewerOpenFile = function (evt) {
    const openFileInputName = PDFViewerApplication.appConfig.openFileInputName;
    document.getElementById(openFileInputName).click();
  };
}
function webViewerPresentationMode() {