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)

/**
     * @param {PDFWorkerParameters} params - Worker initialization parameters.
     */
    constructor({
      name = null,
      port = null,
      verbosity = getVerbosityLevel(),
    } = {}) {
      if (port && pdfWorkerPorts.has(port)) {
        throw new Error("Cannot use more than one PDFWorker per port");
      }
      this.name = name;
      this.destroyed = false;
      this.postMessageTransfers = true;
      this.verbosity = verbosity;
      this._readyCapability = createPromiseCapability();
      this._port = null;
      this._webWorker = null;
      this._messageHandler = null;
      if (port) {
        pdfWorkerPorts.set(port, this);
        this._initializeFromPort(port);
        return;
      }
      this._initialize();
    }
    get promise() {