WKWebView: Do not DCHECK on invalid CertVerifierBlockAdapter::Params.

cert and hostname params are coming from System API and both can
potentially be null. For CertVerifierBlockAdapter client
(web controller) it will be more convenient not to handle a special case
with invalid cert and/or hostname. Instead params error will be handled
in completionHandler block along with other errors.

BUG=462427

Review URL: https://codereview.chromium.org/1231783003

Cr-Commit-Position: refs/heads/master@{#338517}
3 files changed