This RTC_DCHECK is no longer valid when we start sending two-byte header
extensions.
Bug: webrtc:7990
Change-Id: Id6cda6f3647838a0d93aa48528bb0bb4300304d3
Reviewed-on: https://webrtc-review.googlesource.com/c/105104
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Johannes Kron <kron@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25315}