Moves to the instruction for
this().
This method skips all the instructions for computing arguments to this(), which should be placed at the beginning of a constructor body.
This method returns the index of INVOKESPECIAL instruction executing this(). A successive call to next() returns the index of the next instruction following that INVOKESPECIAL.
This method works only for a constructor.
@return the index of the INVOKESPECIAL instruction, or -1if a explicit constructor invocation is not found but super() is found.