MANILA, Philippines — Teenager Tachiana Mangin faltered in the gold medal match against world taekwondo champion Jingyue Ma of China in the women’s under-49 kilogram (kg), 2-0, to cop a silver medal in her Asian Games debut on Friday night. The 18-year-old Mangin was outplayed by the 25-year-old Ma, who showed more precise kicks over the Filipina.