Further un-specialize function arguments

Currently the basic blocks pass generates some synthetic annotations for the arguments. This way the arguments are recorded as "written" in the basic blocks pass and we can find them there. However, they do not show up in the individual states' register arrays. Therefore, we still need special code to deal with them in case of unconditional jumps.

It would be better if the type propagator already performed some synthetic operations to seed the argument registers.