go/loader: minor comment fix.
go/loader: minor comment fix.

TBR=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/157970043

cw2018/tools,magiccao/tools,cw2018/tools,glasser/golang-tools,cmars/tools,glasser/golang-tools,runcom/tools,argandas/tools,argandas/tools,golang/tools,golang/tools,nicot/tools,cmars/tools,glasser/golang-tools,springning/tools,runcom/tools,nicot/tools,runcom/tools,maddyonline/tools,golang/tools,syreclabs/go-tools,jdhenke/tools,golang/tools,argandas/tools,nicot/tools,runcom/tools,magiccao/tools,sshetty10/tools,argandas/tools,josharian/tools,syreclabs/go-tools,magiccao/tools,maddyonline/tools,dmitris/tools,matryer/tools,springning/tools,springning/tools,sshetty10/tools,nicot/tools,syreclabs/go-tools,dmitris/tools,cw2018/tools,matryer/tools,dmitris/tools,dmitris/tools,magiccao/tools,maddyonline/tools,4ad/tools,matryer/tools,springning/tools,jdhenke/tools,syreclabs/go-tools,4ad/tools,maddyonline/tools,cw2018/tools,josharian/tools,sshetty10/tools,4ad/tools,golang/tools,glasser/golang-tools,josharian/tools,syreclabs/go-tools,jdhenke/tools,josharian/tools,cmars/tools,sshetty10/tools,syreclabs/go-tools,cmars/tools,jdhenke/tools,matryer/tools