Update comments in Object.defineProperties tests (Fixes #138)

The expected values were already changed in a previous commit (@49abae4f5e6b38931d86dc9b9d34ae30d9ced2ca),
only the test descriptions still needed to be updated. (Fixes #138)
Merge pull request #139 from anba/issue-138/defineproperties-exception

Update comments in Object.defineProperties tests (Fixes #138)