Several of the CLs that were against the runtime are noted in other
places in the release notes, depending on where they are most
user-visible.

Change-Id: I167dc7ff17a4c5f9a5d22d5bd123aa0e99f5639e
Reviewed-on: https://go-review.googlesource.com/45137Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>