By THÉRÈSE MARGOLIS     The Clínica Dermatólogia Isela Méndez in Colonia Polanco this month became the first and only medical facility in Mexico City to offer Emsculpt, a revolutionary noninvasive procedure that simultaneously burns fat and builds muscle. Designed specifically to target problem areas such as the abdomen, buttocks and thighs to create a more athletic form, Emsculpt technology is the