Make Cast certificate verification enforce constraints specified in the trusted root certificate.

net/data/verify_certificate_chain_unittest/generate-non-self-signed-root.py

 #!/usr/bin/python
 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Certificate chain with 1 intermediary and a trusted root. The intermediary
-however is signed using the MD5 hash. Verification is expected to fail because
-MD5 is too weak."""
+"""Certificate chain with 1 intermediary and a trusted root. The trusted root
+is NOT self signed, however its issuer is not included in the chain or root
+store. Verification is expected to succeed since the root is trusted."""
 
 import common
 
-# Self-signed root certificate (part of trust store).
-root = common.create_self_signed_root_certificate('Root')
+shadow_root = common.create_self_signed_root_certificate('ShadowRoot')
 
-# Intermediary.
+# Non-self-signed root (part of trust store).
+root = common.create_intermediary_certificate('Root', shadow_root)
+
+# Intermediary certificate.
 intermediary = common.create_intermediary_certificate('Intermediary', root)
-intermediary.set_signature_hash('md5')
 
 # Target certificate.
 target = common.create_end_entity_certificate('Target', intermediary)
 
 chain = [target, intermediary]
 trusted = [root]
 time = common.DEFAULT_TIME
-verify_result = False
+verify_result = True
 
 common.write_test_file(__doc__, chain, trusted, time, verify_result)