bugc: give a caller's call JUMP the invoke's arguments - #354

bugc puts an internal call's invoke on two instructions: the caller's JUMP and the callee's entry JUMPDEST. Only the JUMPDEST's copy had arguments. Contexts are postconditions, so a debugger opens the callee's frame on the step after the JUMP, which is the JUMPDEST step, and there the frame had no arguments. They showed up one step later.

The JUMP leaves the arguments on the stack in the same slots the JUMPDEST describes (the JUMPDEST does not change the stack), so the JUMP's invoke now has the same arguments pointer. Both sites build it from one helper, invokeArguments.

call-contexts.test.ts asserted that the caller JUMP has no arguments. That assertion now expects the pointer group, and a new test reads the JUMP's argument pointers against the trace state after the JUMP to check that they give the values passed.

The tail-call back-edge JUMP still has no arguments. This change does not touch it.