TEHRAN — Preparations for the funeral of Iran's slain supreme leader Ali Khamenei were in full swing on Friday, with authorities expecting millions and a coterie of foreign dignitaries to attend the official ceremony. Pakistan, a key mediator in talks between the United States and Iran on ending the Middle East war, said its Prime Minister Shehbaz Sharif would be at the funeral in Tehran on Saturday. China, Afghanistan and Iran's neighbours in the Caucasus region said they would also be sending representatives. Workers were readying Tehran's Grand Mosalla religious complex on Thursday, while security teams stopped passing cars and curious bystanders looked on. "We are planting flowers and watering the shrubs for the farewell ceremony of our martyred guide," said worker Hossein Moghadassi, clad in a hat and a scarf to cover his face as the temperature soared. "People will come from all over Iran. There will be huge crowds." Tehran's chief negotiator Mohammad Bagher Ghalibaf had called on Thursday for a massive turnout at the event as a way to avenge the supreme leader's death in U.S.-Isra