Do not put new cloned instrs back into original CFG.  WrappedIRClosure is
converted to ClosureInterpreterContext which is not usable by the JIT.

This cloning was done for CFG to match interpreter instr list for accurate
debugging.  A followup commit will clone CFG if debug is enabled so that
we have a contention-free CFG (from JIT) and one which has same instrs
as what the interpreter is interpreting.