REGRESSION (r154300): http/tests/security/cross-frame-access-getOwnPropertyDescriptor is failing or crashing on the bots

Reviewed by Geoff Garen.

Previously we allowed cross-frame access to these properties, but hid the descriptors.
Now we allow access, but make them read-only, non-configurable.

* http/tests/security/cross-frame-access-getOwnPropertyDescriptor-expected.txt:
* http/tests/security/cross-frame-access-getOwnPropertyDescriptor.html:
* platform/mac/TestExpectations:
    - Update test/results/expectations.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154379 268f45cc-cd09-0410-ab3c-d52691b4dbfc