The test's server was replying with the stream closure before reading
the test client's request body. This should in theory be handled
better (and golang/go#16029 will be kept open to track it), but that's not
what this test was trying to test anyway.

Instead, make the test do things in the expected order so it can
continue to test its original subject reliably. (It was trying to test
all the orders of optional & optionally fragmented headers in responses.)

Updates golang/go#16029 (flaky http2 TestTransportResPattern_*)
Updates golang/go#11811 (subrepos need to be green)

Change-Id: I631730fce5dad598120bb2d1ea8895e39255d711
Reviewed-on: https://go-review.googlesource.com/24970Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>