@sueloverso, I think we should decide whether to support JSON dump of index cursors before the merge.

If it isn't too hard, I'd suggest we try to make it work, but if it isn't clean, I don't mind if JSON dump only works on table cursors.  After all, this is really intended for use as a dump format, and people generally just dump their primary data -- indices are only used for (online) queries.

If we drop support for JSON dump of indices, we should get rid of this code.