It is time once again to wonder:
Does anyone know less about American politics than Yglesias?
Read here to find out who was booing Trump at the debate.
Read here to find out who Trump was addressing and who he cares about reaching (spoiler: not the people who were booing).
Read here for a reminder of the fact that this issue has already come up - 4 months ago - and it made no difference to the GOP primary.
Update 02/18: And indeed, it doesn't seem to be making a difference this time either.