static shortDelay(realSetTimeout) {
    const delay = 0.01;
    return shaka.test.Util.delay(delay, realSetTimeout);
  }
Returns a Promise which is resolved after a short delay.  This should be
used for cases where we need to wait for a setTimeout(0) or a Promise to
be handled.

@param {function(function(), number)=} realSetTimeout
@return {!Promise}