* FTSE 100 down 0.2 points * U.S. equity market closed for holidays * Anglo American dips as banks revise down estimates * Recent M&A pickup helps support some stocks By David Brett LONDON, Feb 18 (Reuters) - Britain's top shares edged lower on Monday, with the benchmark FTSE 100 index struggling to break through fresh five-year highs as investors temper their long-term bullishness with some short-term caution.