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)

const tmpCanvas = owner.cachedCanvases.getCanvas(
        "pattern",
        dimx.size,
        dimy.size,
        true
      );
      const tmpCtx = tmpCanvas.context;
      const graphics = canvasGraphicsFactory.createCanvasGraphics(tmpCtx);
      graphics.groupLevel = owner.groupLevel;
      this.setFillAndStrokeStyleToContext(graphics, paintType, color);
      graphics.transform(dimx.scale, 0, 0, dimy.scale, 0, 0);
      
      graphics.transform(1, 0, 0, 1, -x0, -y0);
      this.clipBbox(graphics, bbox, x0, y0, x1, y1);
      graphics.executeOperatorList(operatorList);
      this.ctx.transform(1, 0, 0, 1, x0, y0);
      
      
      this.ctx.scale(1 / dimx.scale, 1 / dimy.scale);
      return tmpCanvas.canvas;
    },
    getSizeAndScale: function TilingPattern_getSizeAndScale(
      step,
      realOutputSize,
      scale
    ) {
      
      step = Math.abs(step);