TORONTO/HONG KONG, Nov 30 (Reuters) - From Sydney to Toronto, mainland Chinese have stepped up protests this week, with demands to end the world's most stringent COVID-19 restrictions evolving into calls to "free China" and for President Xi Jinping to step down. Overseas-based Chinese and their supporters rallied in Sydney, Tokyo, Hong Kong, New York and Toronto, with more protests planned in coming days. "Free China. Xi Jinping step down," about 30 people shouted in Toronto on Tuesday. At Harvard University in Massachusetts, dozens chanted: "No more lies" and "no more censorship." China's foreign ministry did not immediately respond to...