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)

transY = "-" + textLayerDiv.style.height;
          break;
        case 270:
          transX = "-" + textLayerDiv.style.width;
          transY = 0;
          break;
        default:
          console.error("Bad rotation value.");
          break;
      }
      textLayerDiv.style.transform =
        `rotate(${textAbsRotation}deg) ` +
        `scale(${scale}) ` +
        `translate(${transX}, ${transY})`;
      textLayerDiv.style.transformOrigin = "0% 0%";
    }
    if (redrawAnnotations && this.annotationLayer) {
      this._renderAnnotationLayer();
    }
    if (this.xfaLayer) {
      this._renderXfaLayer();
    }
  }
  get width() {
    return this.viewport.width;
  }
  get height() {
    return this.viewport.height;
  }
  getPagePoint(x, y) {