Description: calls an interface method
n is the number of arguments to the method
the long method name is really a path name, the name of the interface,
the parenthesized argument list of the method called, and the return type.
Primitive types are represented by their capitalized first letter, ie I for an integer.
Constructors are path followed by <init>()V
invoke java/lang/Runnable/run()V ; runnableOject.run()
ExceptionsNullPointerException if object ref is null
StackOverflowError if you run ou t of room on stack
back to opcode reference.