Fold the shutdown flags into one, take the smallest frame to the wire minimum, drop the speed column

loss.go

@@ -36,8 +36,8 @@ func newLossWindows(tx []*txStats) []lossWindow {
 	return w
 }
 
-// A sequence number is only judged once it falls out of the window, so frames
-// still queued in another rx worker are never miscounted as lost.
+// A sequence number is only judged once it falls out of the window, so a frame
+// that has arrived but not yet been drained is never miscounted as lost.
 //
 // Reports whether the sequence number could have come off the wire at all. One
 // above what the sender has reached is a damaged header rather than a gap, and
@@ -53,8 +53,9 @@ func (w *lossWindow) observe(seq uint64) bool {
 	}
 	w.mu.Lock()
 	if !w.inited {
-		// Start half a window below the first sequence seen, so frames another
-		// rx worker is still holding land inside the window rather than late.
+		// Start half a window below the first sequence seen, so anything the
+		// sender put on the wire before it lands inside the window rather than
+		// below the base.
 		if seq > lossSlots/2 {
 			w.base = seq - lossSlots/2
 		}