Fix toJsParams not properly respecting types of fields
Fix toJsParams not properly respecting types of fields

This would cause problems with large (u)int64_t fields

martindale/node-capnp,kentonv/node-capnp,martindale/node-capnp,jzjzjzj/node-capnp,dwrensha/node-capnp,dwrensha/node-capnp,dwrensha/node-capnp,martindale/node-capnp,martindale/node-capnp,dwrensha/node-capnp,jzjzjzj/node-capnp,jzjzjzj/node-capnp,kentonv/node-capnp,jzjzjzj/node-capnp,kentonv/node-capnp