This prepares for allowing use making arithmetic operators constexpr.
This also makes it easier to use for comparisons with offsets.
Now a > b + 10 ms works even if b is infinite.
Bug: webrtc:9574
Change-Id: Ie36092b72c2ec0f0c541641199a39155f5a796f3
Reviewed-on: https://webrtc-review.googlesource.com/96820
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24530}