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)

}
        handled = true;
        break;
      case 82: 
        PDFViewerApplication.rotatePages(-90);
        break;
    }
  }
  if (!handled && !isViewerInPresentationMode) {
    
    
    
    if (
      (evt.keyCode >= 33 && evt.keyCode <= 40) ||
      (evt.keyCode === 32 && curElementTagName !== "BUTTON")
    ) {
      ensureViewerFocused = true;
    }
  }
  if (ensureViewerFocused && !pdfViewer.containsElement(curElement)) {
    
    
    
    pdfViewer.focus();
  }
  if (handled) {
    evt.preventDefault();
  }
}
function beforeUnload(evt) {