Check that all properties are processed in NameDictionary::CopyEnumKeysTo.

BUG=372579
LOG=N
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/306663002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21571 ce2b1a6d-e550-0410-aec6-3dcde31c8c00