Handle unserializable unicode 1019729

https://bugzilla.mozilla.org/show_bug.cgi?id=1019729

Turns out if you encode to UTF-8 and don't JSON serialize/deserialize to spidermonkey (but still do on the way out) things just work... maybe?

@mattbasta maybe you have some insight as to why the JSON serialization was happening on the way in the begin with.
do you really want a catch all except here?