Check keyUsage bits in QUIC and Web Packaging..

This introduces a wrapper for SignatureVerifier when the public key
comes from a certificate.

Bug: 795086, 803774
Change-Id: I177e4a2b3ea1b94afbac914c051be9f2b8b67985
Reviewed-on: https://chromium-review.googlesource.com/924349
Commit-Queue: David Benjamin <[email protected]>
Reviewed-by: Ryan Sleevi <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Cr-Commit-Position: refs/heads/master@{#558053}
19 files changed