async findVerticalRefreshRateForDisplayPoint(x, y) {
    await this.readyPromise;

    let ret;
    for (const { top, bottom, left, right, vRefreshRate } of this.geometry) {
      if (left <= x && x < right && top <= y && y < bottom) {
        ret = ret === undefined ? vRefreshRate : Math.min(ret, vRefreshRate);
      }
    }

    return ret;
  }
Computes the vertical refresh rate of the displays at a given display point.

If any displays overlap at the given display point, the return result will
be the minimum of the vertical refresh rates of each physical device displaying
at that effective point.

This method is asynchronous due to the implementation of addDisplayChangeListener;
it waits for a valid display configuration to be captured before returning the
best possible refresh rate.

@param {number} x The vertical offset of the display point
@param {number} y The horizontal offset of the display point

@returns {number | undefined} The vertical refresh rate at the given display point,
  or undefined if the given display point is out of bounds of the available display space.