task: #3588897 Widen the script/stylesheet bytes assertion ranges in performance tests

    $values = [];

    foreach ($expected as $name => $metric) {

      if (in_array($name, $assertRange)) {

        $this->assertCountBetween($metric - 500, $metric + 500, $performance_data->{"get$name"}(), "Asserting $name");

        $this->assertCountBetween($metric - 2000, $metric + 2000, $performance_data->{"get$name"}(), "Asserting $name");

        unset($expected[$name]);

      }

      else {