Iran's parliament is trying to turn fears of foreign infiltration into law. But as lawmakers work through the legislation, the debate is exposing an increasingly awkward question for the Islamic Republic: How far should the state go in policing Iranians' contact with the outside world? At the center of that debate is Parliament Speaker Mohammad Baqer Qalibaf, who, at least publicly, is doing a balancing act. He has defended the need for tougher measures against foreign infiltration while warning that the current draft of the legislation goes too…