By Libby George and Karin Strohecker LONDON, Dec 19 (Reuters) - Emerging markets defied tariffs, trade wars and global turmoil to notch up stellar double-digit returns in 2025, and investors are hopeful of a repeat performance next year. Years of painful fiscal choices and central bankers who made all the right calls have left once-risky ​countries looking solid in the face of political and economic clouds in the United States and Europe, and rising geopolitical fragmentation. "There are a lot of tailw ...