fixes an incorrect redundancy shift and add tests that would have caught this bug.
BUG=webrtc:11640
Change-Id: I6fe2fb21587fffc5fee4d403ac898e12d525a1cd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/224120
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Commit-Queue: Henrik Lundin <henrik.lundin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34702}