Prevent DCHECK failure in QUIC congestion control I saw a DCHECK failure in GeneralLossAlgorithm::DetectLosses where least_in_flight_ was being compared even though it was uninitialized. I'm unable to reproduce this reliably but this CL looks correct from code inspection. gfe-relnote: n/a, no behavior change PiperOrigin-RevId: 304603107 Change-Id: I8557403886143d763fd6c77be3a7ecbf76628ae2