Issue with finding type-signature for Procedure Type Arguments

[TheRealMichaelWang]

Just realized that because of recent optimizations made for type parameter information registers for procedures, not all generics have their runtime type-signature available, hence the type signature would either have to be derived from:

• The interface the type-param requires the type-argument to implement. This, however, is not type safe.
• Assign another silent register-parameter for the said type argument that needs to have a type signature available, much like its generic counterparts that don't implement any interface types. This is probably the best solution.

Note that this issue only applies to the upcasting branch