ArrayObject::offsetExists - Fix check on offsetExists

[mwillbanks]

Fix for issue #4832 where we checked isset vs. array_key_exists.

[weierophinney]

Looks like we need to use version sniffing to determine whether to do array_key_exists or isset?

[mwillbanks]

negative; it's actually far worse than that... the contract in arrayobject when we turn it to references is what starts to cause the issue. i'm going to dig a bit deeper when i have some more time tomorrow :)

[weierophinney]

@mwillbanks Any ideas on how to proceed on this? If this approach won't work, should I close this PR?

[mwillbanks]

@weierophinney attempted about 3 or 4 ways to resolve this. The closest I was able to get was turning the metadata into an arrayobject but that caused other tests to fail along with the request access time not to come through in the tests. I think the only real way to resolve this is to remove arrayobject completely from session.