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* Remove some older language about trust anchors, and consistently refer
  to "root certificate" instead

* Omit trivia about the chain (like count of certificates), and focus
  description on what makes it special

* Don't refer to expected validation success/failure in the chain
  descriptions. Instead this logically belongs in the .test file (I didn't
  add comments to the .test files... however the error messages should be
  self-descriptive).

Review-Url: https://codereview.chromium.org/2951403002
Cr-Commit-Position: refs/heads/master@{#481816}