As protesters descended on the Michigan Statehouse Tuesday, legislators passed a controversial "right-to-work" measure that would weaken unions' power. The House approved two bills, which the Senate already passed last week. Both chambers are dominated by Republicans. Gov. Rick Snyder, a Republican, has said he will sign the legislation, which would allow workers at union-represented employers to forgo paying dues. Thousands of people, many of them union workers, gathered outside the statehouse, chanting and holding signs as snow fell. At least three schools were closed as teachers traveled to Lansing to protest. There are 23 states which have right-to-work laws, mostly in the South and western plains states, where union membership is…