Make intercepted properties retrievable only by getter to be not enumerable.

Make intercepted properties retrievable only by getter to be not enumerable.

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