callback doesn't accept functions nested in objects

```
http://json-lipsum.appspot.com/?callback=obj.fn

Using callback=obj.fn should return obj.fn({...})
But it ignores callback.

YUI has a jsonp module that will temporarily un-sandbox a function. Like this:
callback=YUI.Env.JSONP.yui_3_2_0_1_1286352293710625

```

Original issue reported on code.google.com by `david...@gmail.com` on 6 Oct 2010 at 8:26

No source file or test is named in the issue. Start by reproducing the JSONP request with callback=obj.fn and compare it with the documented top-level callback behavior; also inspect the YUI-style nested callback example. Done means nested callback names invoke the returned JSON rather than being ignored.

Written by the indexing model from the issue text.