discardedFrames property

@override Stream<({int bytes, int streamId})> get discardedFrames

Reports skipped bytes as they ARRIVE.

Crediting the DECLARED length instead is worse than the wedge it fixes: a peer sending nothing but 9-byte headers gets its window topped up for free, which is the one thing flow control exists to stop.

Implementation

@override
Stream<({int streamId, int bytes})> get discardedFrames =>
    _discardedCtl.stream;