WASHINGTON — Democrats powered a massive $3 trillion coronavirus relief bill through the House on Friday, an election-year measure designed to brace a U.S. economy in free falland a health care system struggling to contain a pandemic still pummeling the country.The 208-199 vote, over strong Republican opposition, advances what boils down to a campaign-season display of Democratic economic and health-care priorities. It has no chance of becoming law as written, but will likely spark difficult negotiations with the White House and Senate Republicans.Any product would probably be the last major C…