go.tools/go/types: check type-checker against $GOROOT/test
go.tools/go/types: check type-checker against $GOROOT/test

R=adonovan
CC=golang-dev
https://codereview.appspot.com/12070044

t-yuki/go.tools.old,t-yuki/go.tools.old,tmc/mirror-go.tools,tmc/mirror-go.tools,tmc/mirror-go.tools,t-yuki/go.tools.old