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)

callback,
      params,
      objs,
      commonObjs,
      operatorList,
      pageIndex,
      canvasFactory,
      webGLContext,
      useRequestAnimationFrame = false,
      pdfBug = false,
    }) {
      this.callback = callback;
      this.params = params;
      this.objs = objs;
      this.commonObjs = commonObjs;
      this.operatorListIdx = null;
      this.operatorList = operatorList;
      this._pageIndex = pageIndex;
      this.canvasFactory = canvasFactory;
      this.webGLContext = webGLContext;
      this._pdfBug = pdfBug;
      this.running = false;
      this.graphicsReadyCallback = null;
      this.graphicsReady = false;
      this._useRequestAnimationFrame =
        useRequestAnimationFrame === true && typeof window !== "undefined";
      this.cancelled = false;
      this.capability = createPromiseCapability();
      this.task = new RenderTask(this);