Assert default SSLSocketFactory and HostnameVerifier actually used.

This adds tests to assert that default SSLSocketFactory and
HostnameVerifier of HttpsURLConnection are actually used for new
instances of HttpsURLConnection.

The contract of HttpsURLConnection.get/setDefaultHostnameVerifier
and HttpsURLConnection.get/setDefaultSSLSocketFactory is that the
HostnameVerifier and SSLSocketFactory instances returned/set via
these methods are used for new instances of HttpsURLConnection.

Bug: 18481199
Change-Id: Id976c2fc31f0e3efed9284860aa35144a729dabb