The Japan opening of the hit film “Barbie” was dealt additional setbacks as an online petition gained steam calling on Hollywood studios to disavow a grassroots marketing movement that made light of nuclear holocaust. A Change.org petition collected more than 16,000 signatures over two days as of Thursday, demanding that Warner Bros and Universal Pictures, the studio behind the “Oppenheimer” biopic, call a halt to the “Barbenheimer” hashtag that has helped make the film a global blockbusters. “Barbie”, which stars Margot Robbie in the title role, has grossed more than $800 million in worldwide box office, while the film about...