Washington - U.S. President Donald Trump heads for a superpower summit with Chinese counterpart Xi Jinping next week hoping the Iran war will not spoil the mood in Beijing.Trump will be expecting a lavish welcome at the high-stakes meeting, which he delayed in March because of the Middle East conflict.But the war will still loom large over his first visit to China since 2017, which is supposed to focus on easing tensions over trade and Taiwan between the world's largest economies.