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)

this.imageLayer.appendImage({
          imgData,
          left: position[0],
          top: position[1],
          width: width / currentTransform[0],
          height: height / currentTransform[3],
        });
      }
      this.restore();
    }
    paintInlineImageXObjectGroup(imgData, map) {
      if (!this.contentVisible) {
        return;
      }
      const ctx = this.ctx;
      const w = imgData.width;
      const h = imgData.height;
      const tmpCanvas = this.cachedCanvases.getCanvas("inlineImage", w, h);
      const tmpCtx = tmpCanvas.context;
      putBinaryImageData(tmpCtx, imgData, this.current.transferMaps);
      for (let i = 0, ii = map.length; i < ii; i++) {
        const entry = map[i];
        ctx.save();
        ctx.transform.apply(ctx, entry.transform);
        ctx.scale(1, -1);
        ctx.drawImage(
          tmpCanvas.canvas,
          entry.x,
          entry.y,
          entry.w,