Improve HTTPS error page text when SubjectAltName missing

In M58, Chrome deprecated fallback to SubjectCN when determining
certificate validity.

This changelist improves the error string shown when a Certificate Name
Mismatch error occurs and the certificate does not specify any DNS
names in the X.509 SubjectAltNames extension.

BUG=708268

Review-Url: https://codereview.chromium.org/2868733003
Cr-Commit-Position: refs/heads/master@{#472468}
2 files changed