Add new certificate error code
ERR_CERT_WEAK_SIGNATURE_ALGORITHM and certificate status
flag CERT_STATUS_WEAK_SIGNATURE_ALGORITHM.  Note that I
didn't add new load flag
LOAD_IGNORE_CERT_WEAK_SIGNATURE_ALGORITHM.

Allow users to accept MD2 certificates as certificates
signed using a weak signature algorithm.  MD4 certificates
are still treated as invalid certificates.

R=jar,jcampan
BUG=http://crbug.com/18725
TEST=none
Review URL: http://codereview.chromium.org/165504

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@23497 0039d316-1c4b-4281-b951-d872f2087c98
9 files changed