Fix off-by-one bug for methods with non-inline param list.
Fix off-by-one bug for methods with non-inline param list.

martindale/node-capnp,kentonv/node-capnp,martindale/node-capnp,kentonv/node-capnp,kentonv/node-capnp,martindale/node-capnp,martindale/node-capnp