If we're going to do this for Go 1.6 we might as well do it now
and find out what breaks.

Change-Id: I8306b7829d8d13b564a1466c902ec6ba1a5a58c1
Reviewed-on: https://go-review.googlesource.com/13967Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>