NEW YORK — If the beginning of the holiday season is any indication, it could be a merry mobile Christmas for shoppers.For the first time, there’s expected to be more people visiting retailers’ websites through their smartphones than on desktop computers or tablets during the first weekend of the holiday shopping season that began on Thanksgiving Day.Mobile traffic during the five-day start to what is typically the busiest shopping period of the year is expected to reach 56.9 percent of total traffic, up …