Democrats and Republicans are quick to talk up a bipartisan infrastructure deal. Yet neither party wants to take the political risk of paying for it when all options are toxic -- including the obvious choice of raising the national gas tax. Increasing the gas tax is so politically fraught that it hasn’t been touched in 26 years and it didn’t even come up at a meeting at the White House Tuesday between President Donald Trump, House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer to discuss an infrastructure plan. While they agreed broadly on the need to upgrade roads,...