Removing specs from finagle/finagle-native test.

Going along with the corresponding issue https://github.com/twitter/finagle/issues/290 and my other PR on the subject https://github.com/twitter/finagle/pull/292


The `CertChainOutput` that you create at line 56 will fail because you never create this context (never execute the constructor to be precise).
In general, I agree with you, but here you don't share anything with the instance of `Context`, you're just counting on the side effect of creating an instance.