doc/go1.1.html: document division by zero change from CL 6710045

I am still not convinced this is a change we should make, but at least
documenting it will keep us from forgetting it as we get closer to Go 1.1.

R=golang-dev, minux.ma
CC=golang-dev
https://codereview.appspot.com/7226064
A+C: Michael Teichgr?ber (individual CLA)

Generated by addca.

R=gobot
CC=golang-dev
https://codereview.appspot.com/7237057
net: SplitHostPort: adjust error message for missing port in IPv6 addresses

An hostport of "[::1]" now results in the same error message
"missing port in address" as the hostport value "127.0.0.1",
so SplitHostPort won't complain about "too many colons
in address" anymore for an IPv6 address missing a port.

Added tests checking the error values.

Fixes issue 4526.

R=dave, rsc, mikioh.mikioh
CC=golang-dev
https://codereview.appspot.com/7038045

Committer: Russ Cox <rsc@golang.org>