Update SSL error handling code to account for Subject CN deprecation

Update SSL error handling code to account for Subject CN deprecation

In Issue 308330, Chrome deprecated the use of the Subject CN field in
certificate hostname validation. However, the certificate error
interstitial and error classification logic were left unchanged,
leading to misleading error messages and doomed error recovery attempts
in the event that a certificate lacked SubjectAltNames.

In this change, Chrome's Certificate Error interstitial and error
recovery will no longer fallback to the certificate's Subject CN field
when evaluating the certificate's valid dns names.

BUG=703614
Review-Url: https://codereview.chromium.org/2777383002
Cr-Commit-Position: refs/heads/master@{#462230}
(cherry picked from commit c7484f52b8ceb68e4334cad505e894aeef6cba83)