Hillary Clinton dropped by the resort island of Martha’s Vineyard over the weekend to pick up more than $1 million in campaign contributions during an elegant party at the summer home of one of her most devoted supporters. Thirty people contributed $50,000 apiece to attend the Saturday night function at the home of Lynn Forester de Rothschild, a wealthy investment manager so committed to Clinton that she couldn’t bring herself to vote for then-Sen. Barack Obama after he defeated her candidate in 2008. President Obama and First Lady Michelle Obama were on the island at the time of the Saturday...