Possible scope leak in Nashorn

[André Bargull]

> Thanks, I adapted the code to use ScriptUtils.wrap() and encountered a
> strange situation where JSON.stringify returns undefined for a valid JS
> object. Maybe another scope problem?
>
> Here is a reproducer:https://gist.github.com/purplefox/7893408

No, it's not a  scope problem. JSON.stringify isn't able to process 
ScriptObjectMirror objects, see ll. 263-270 in NativeJSON.java [1].

- André

[1] 
http://hg.openjdk.java.net/nashorn/jdk8/nashorn/file/tip/src/jdk/nashorn/internal/objects/NativeJSON.java