net/http: update bundled http2

Updates x/net/http2 to git rev 2e9cee70 for https://golang.org/cl/18801

Change-Id: I4689c5704bb0b12d569925f81c3e699857ea463e
Reviewed-on: https://go-review.googlesource.com/18931Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/http/h2_bundle.go

@@ -2098,6 +2098,8 @@ func http2validHeaderFieldName(v string) bool {
 // validHeaderFieldValue reports whether v is a valid header field value.
 //
 // RFC 7230 says:
+//  field-value    = *( field-content / obs-fold )
+//  obj-fold       =  N/A to http2, and deprecated
 //  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
 //  field-vchar    = VCHAR / obs-text
 //  obs-text       = %x80-FF
@@ -2117,7 +2119,7 @@ func http2validHeaderFieldName(v string) bool {
 // strings that begin or end with SP or HTAB.
 func http2validHeaderFieldValue(v string) bool {
 	for i := 0; i < len(v); i++ {
-		if b := v[i]; b < ' ' && b != '\t' {
+		if b := v[i]; b < ' ' && b != '\t' || b == 0x7f {
 			return false
 		}
 	}