CRANS MONTANA, Switzerland — Suddenly the overall title is not looking so certain for Mikaela Shiffrin after Ilka Stuhec won a super-G race on Saturday. There was also a worrying crash for Lindsey Vonn on a disappointing day for American skiers. Entering this weekend’s races in Crans Montana, Shiffrin held more than a 400-point lead in the standings over her next active challenger, Sofia Goggia of Italy.