http2: remove duplicate map lookups in checkConnHeaders

Change-Id: I3fa5b27a4846807e8ed1265d696929037b77861b
Reviewed-on: https://go-review.googlesource.com/30160
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed