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)

tmpCanvas = cachedCanvases.getCanvas(
        "mesh",
        paddedWidth,
        paddedHeight,
        false
      );
      const tmpCtx = tmpCanvas.context;
      const data = tmpCtx.createImageData(width, height);
      if (backgroundColor) {
        const bytes = data.data;
        for (i = 0, ii = bytes.length; i < ii; i += 4) {
          bytes[i] = backgroundColor[0];
          bytes[i + 1] = backgroundColor[1];
          bytes[i + 2] = backgroundColor[2];
          bytes[i + 3] = 255;
        }
      }
      for (i = 0; i < figures.length; i++) {
        drawFigure(data, figures[i], context);
      }
      tmpCtx.putImageData(data, BORDER_SIZE, BORDER_SIZE);
      canvas = tmpCanvas.canvas;
    }
    return {
      canvas,
      offsetX: offsetX - BORDER_SIZE * scaleX,
      offsetY: offsetY - BORDER_SIZE * scaleY,
      scaleX,
      scaleY,
    };