message: transport/send: Don't check stream.send_data_ready() when generating frames
  send_data_ready() means that the application can send more data. That has
  nothing to do with whether there is data in the buffer that is available
  for actually sending.
  Uncomment the part of the test this bug (along with 12f18a2) caused to
  fail.
diff: @@ -1959,7 +1959,6 @@ impl FrameGenerator for StreamGenerator {
  }
  for (stream_id, stream) in &mut conn.send_streams {
  - if stream.send_data_ready() {
  let fin = stream.final_size();
  if let Some((offset, data)) = stream.next_bytes(mode) {
  qtrace!(
  @@ -1994,7 +1993,6 @@ impl FrameGenerator for StreamGenerator {
  ));
  }
  }
  - }
  None
  }
  }
  @@ -2633,11 +2631,10 @@ mod tests {
  assert_eq!(received, 140);
  assert_eq!(fin, false);
  - // TODO(agrover) : fix this: iter.next() on the next line returns None.
  - // let (stream_id, stream) = iter.next().unwrap();
  - // let (received, fin) = stream.read(&mut buf).unwrap();
  - // assert_eq!(received, 60);
  - // assert_eq!(fin, true);
  + let (stream_id, stream) = iter.next().unwrap();
  + let (received, fin) = stream.read(&mut buf).unwrap();
  + assert_eq!(received, 60);
  + assert_eq!(fin, true);
  }
  /// Drive the handshake between the client and server.
  