Donald Trump thinks she would make a fine vice president. One conservative cites her as one of the reasons to vote for Trump. Ivanka Trump, 34, wife, mother of three, fashion entrepreneur, advocate for women’s empowerment and an executive vice president in her father’s real estate empire, has eschewed an official role in his campaign. But she’s a critical adviser and perhaps the unorthodox campaigner’s most important surrogate, especially with his wife, Melania, seemingly more comfortable on the sidelines. It will be Ivanka who introduces her father to the nation Thursday as he delivers what could be the most important...