PORTLAND, Ore. — Protesters in the Pacific Northwest smashed windows at a Democratic Party headquarters, marched through the streets and burned an American flag on Wednesday in a strident challenge by antifascist and racial-justice protesters to the new administration of President Biden, whose promised reforms, they declared, “won’t save us.” In Portland, Ore., lines of federal agents in camouflage — now working under the Biden administration — blanketed streets with tear gas and unleashed volleys of welt-inducing pepper balls as they confronted a crowd that gathered outside an Immigration and Customs Enforcement building near downtown. Some in the crowd later...