Handlify JSObject::CanSetCallback.

Also use temporary wrapper functions where possible to mark progress.

R=ishell@chromium.org

Review URL: https://codereview.chromium.org/172503002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19743 ce2b1a6d-e550-0410-aec6-3dcde31c8c00