Edition: Singapore Indonesia Asia US/UK (Corrects typographical error in headline) By Isla Binnie and Naomi Rovnick NEW YORK/LONDON :Wall Street indexes posted modest gains and oil prices dipped on Wednesday as investors weighed the impacts of a Middle East conflict and a U.S. rate decision on a global economy already grappling with uncertainty stemming from U.S. economic policy. Brent crude oil prices initially extended their recent rise as the Israel-Iran air war entered its sixth day,