function complete(error) {
        self.renderInProgress = false;
        if (self.destroyed) {
          delete self.operatorList;
          delete self.displayReadyPromise;
        }

        if (error)
          promise.reject(error);
        else
          promise.resolve();
      }
Begins the process of rendering a page to the desired context.
@param {object} params A parameter object that supports:
{
  canvasContext(required): A 2D context of a DOM Canvas object.,
  textLayer(optional): An object that has beginLayout, endLayout, and
                       appendText functions.
}.
@return {Promise} A promise that is resolved when the page finishes
rendering.