JOHANNESBURG, June 27 (Reuters) - Technology investor Naspers (NPNJn.J) on Tuesday reported a 78% slump in annual profit, led by a drop in the contribution from China's Tencent (0700.HK) which accounts for the bulk of earnings and revenue for the South African investor. Its headline earnings per share, a profit measure, from continuing operations dropped to 119 U.S. cents for the year ended March 31, from 547 cents posted a year ago. Naspers, which has its global investments housed in Amsterdam-listed Prosus (PRX.AS), , draws over two-thirds of its revenue from Tencent. Its investment in Tencent, where it holds over...