go/types: remove surplus (obsolete) lines from test expectation.
go/types: remove surplus (obsolete) lines from test expectation.

Also add assertion that there are no surplus lines.

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/151890043

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