Fix crash when using Object.getOwnPropertyDescriptor on an API defined callback property.
Fix crash when using Object.getOwnPropertyDescriptor on an API defined
callback property.

Return undefined for Object.getOwnPropertyDescriptor on an API defined
callback properties for now.

Review URL: http://codereview.chromium.org/542074

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@3605 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh