utils.getKeysOfDefinedProperties: Don't add 'message' when working with an Error instance where it's enumerable for some reason.
utils.getKeysOfDefinedProperties: Don't add 'message' when working with an Error instance where it's enumerable for some reason.

Fixes test added in e678d93cf in Phantom.js.

alexjeffburke/unexpected,bruderstein/unexpected,bruderstein/unexpected,alexjeffburke/unexpected,unexpectedjs/unexpected