WASHINGTON — The House accomplished something unusual Wednesday in passing with broad, bipartisan support a roughly $79 billion tax cut package that would enhance the child tax credit for millions of lower-income families and boost three tax breaks for businesses, a combination that gives lawmakers on both sides of the political aisle coveted policy wins.Prospects for the measure becoming law are uncertain with the Senate still having to take it up, but for a House that has struggled to get bills of consequence over …