5.1.2 Should wait for settings ACK

[danielkec]

5.1.2 Tests Stream concurrency limit by setting initial window size to 0.

Problem is that the test is racing against asynchronously handled flow-control on some server impls.

Test should wait for settings ACK before opening first stream.

h2spec/http2/5_1_2_stream_concurrency.go

Lines 34 to 54 in af83a65

	// Set INITIAL_WINDOW_SIZE to zero to prevent the peer from
	// closing the stream.
	settings := http2.Setting{
	ID: http2.SettingInitialWindowSize,
	Val: 0,
	}
	conn.WriteSettings(settings)
	headers := spec.CommonHeaders(c)
	blockFragment := conn.EncodeHeaders(headers)
	for i := 0; i <= int(maxStreams); i++ {
	hp := http2.HeadersFrameParam{
	StreamID: streamID,
	EndStream: true,
	EndHeaders: true,
	BlockFragment: blockFragment,
	}
	conn.WriteHeaders(hp)
	streamID += 2
	}

[robaho]

There are more problems with this test, see #139