In QUIC, incrementally calculate newly acked packets. Protected by FLAGS_quic_reloadable_flag_quic_use_incremental_ack_processing2.

Merge internal change: 187526927

R=rch@chromium.org

Change-Id: Iae1d28a17d693d11331b6cf7e9e5f741084ffd9e
Reviewed-on: https://chromium-review.googlesource.com/946329
Commit-Queue: Fan Yang <fayang@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540823}
11 files changed