- Unsupported members should throw NotSupportedException instead of
NotImplementedException per MSDN docs for CanRead/CanSeek/CanWrite.
- Position should throw NotSupportedException when CanSeek is false.
- FrameRequestStream.Flush/FlushAsync should not throw
NotImplementedException.
- Use expression-bodied members for CanRead/CanSeek/CanWrite on
FrameRequestStream to match FrameResponseStream.
- Provide no-op override of LibuvStream.FlushAsync to match Flush.
8f7c0ff041
