fmt: fix allocation test With new interface allocation rules, the old counts were wrong and so was the commentary.
fmt: fix allocation test
With new interface allocation rules, the old counts were wrong and
so was the commentary.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/142760044

wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old