Public Policy Polling is out with a new survey this morning on the gay marriage referendum likely to be on the Maryland ballot this fall. It's historic, because it shows that Maryland is likely to pass—by a wide margin—the referendum holding up the bill that lawmakers passed in late February. It's incredible because of the shift in previous polls, particularly among black voters in Maryland. Check out this flip: In March, 56 percent of black respondents said they would vote against the law, with only 39 percent supporting it. Now, 55 percent of black voters plan to support it, with only 36...