Many Hollywood celebrities, appalled by President Trump, are ready to dive into the midterm elections. But there's also a sense of caution, and in some cases retreat, after their enormous support failed to push Hillary Clinton over the finish line in 2016. Sunday marked 100 days until Election Day, and at least one expert on the entertainment industry and politics says the next three months could see an explosion of celebrity involvement. “I would not be surprised that, given this more highly politicized environment of Hollywood and the frustration of many celebrities of the outcome of the 2016 election, that...