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)

case "FitBV":
        x = destArray[2];
        width = pageWidth;
        height = pageHeight;
        scale = "page-height";
        break;
      case "FitR":
        x = destArray[2];
        y = destArray[3];
        width = destArray[4] - x;
        height = destArray[5] - y;
        const hPadding = this.removePageBorders ? 0 : SCROLLBAR_PADDING;
        const vPadding = this.removePageBorders ? 0 : VERTICAL_PADDING;
        widthScale =
          (this.container.clientWidth - hPadding) / width / CSS_UNITS;
        heightScale =
          (this.container.clientHeight - vPadding) / height / CSS_UNITS;
        scale = Math.min(Math.abs(widthScale), Math.abs(heightScale));
        break;
      default:
        console.error(
          `${this._name}.scrollPageIntoView: ` +
            `"${destArray[1].name}" is not a valid destination type.`
        );
        return;
    }
    if (!ignoreDestinationZoom) {
      if (scale && scale !== this._currentScale) {
        this.currentScaleValue = scale;
      } else if (this._currentScale === UNKNOWN_SCALE) {