Alibaba Group Holding Ltd. (BABA)’s proposal for what could be the largest initial stock offering in U.S. history is sailing through Washington with few bumps. Alibaba owes its success navigating Washington’s political shoals in part to a handful of key hires over the past three years. The Securities and Exchange Commission — the principal regulatory hurdle Alibaba must clear before raising perhaps $20 billion — has shown no sign it will decline to approve the stock sale that could come as early as next month.