Nikkei down as Aso plays down foreign bond buy talk, Fanuc weighs

* Aso's comment not considering buying foreign bonds sours mood * BOJ governor appointment, Abe's visit to U.S. on focus * Fanuc's fall weighs on index * Bridgestone pulls up tyre companies on strong earnings By Ayai Tomisawa TOKYO, Feb 19 (Reuters) - Japan's Nikkei share average edged down on Tuesday as Japanese Finance Minister Taro Aso played down talk of foreign bond buying by the central bank, while index heavyweight Fanuc Corp dropped on weak machine tool orders from C