net/http: update bundled http2
Updates x/net/http2 to git rev
5916dcb1 for:
* http2, lex/httplex: make Transport reject bogus headers before sending
https://golang.org/cl/23229
* http2: reject more trailer values
https://golang.org/cl/23230
Fixes #14048
Fixes #14188
Change-Id: Iaa8beca6e005267a3e849a10013eb424a882f2bb
Reviewed-on: https://go-review.googlesource.com/23234
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>