Currently if there is no query callback, V8 finds out intercepted properties'
attributes using getter: if getter returns not empty handle V8 treats
such a property as property with NONE attribues which means this property
is enumerable.

However, if there is no enumerator, this property cannot be enumerated.
Thus I think we should treat such properties as not enumerable.

Drawback of this approach is now one has to implement both query and enumerator
callbacks to implement enumerable intercepted properties.

BUG=725

Review URL: http://codereview.chromium.org/2270005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4751 ce2b1a6d-e550-0410-aec6-3dcde31c8c00