[[DefineOwnProperty]] should always return true/false (or throw an exception), never undefined.
[[DefineOwnProperty]] should always return true/false (or throw an exception), never undefined.

Note that this is not an observable behavior, but following the principle of
least surprise, we should follow the spec. Additional (extremely tiny) bonus:
Some ICs see fewer values => better code.
Review URL: http://codereview.chromium.org/8352004

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@9706 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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