goprotobuf: Revert part of 39eef1b13365.
goprotobuf: Revert part of 39eef1b13365.

This gets goprotobuf working with release.r58.
After tagging, I'll revert this change.

R=adg
TBR=adg
CC=golang-dev
http://codereview.appspot.com/4631082

fuchsia-mirror/third_party-github.com-golang-protobuf,jeremyletang/protobuf,trdata/protobuf,ArtemTeleshev/go-protobuf,jrbarron/protobuf,daemonl/protobuf,ekle/protoc-gen-goweb_test,alskjstl/protobuf,velocity-toolkit/protobuf-1,golang/protobuf,qinlodestar/protobuf,golang/protobuf,tamird/protobuf-2,hailocab/protobuf,fuchsia-mirror/third_party-github.com-golang-protobuf,jmptrader/protobuf-1,kung-foo/protobuf,eduardiazf/protobuf,csuideal/protobuf,francoishill/protobuf,mwitkow-io/protobuf,linkedin-inc/protobuf,adnaan/protobuf,trdata/protobuf,tamird/protobuf-2,skyportsystems/go-protobuf,aoeu/protobuf,skyportsystems/go-protobuf,ekle/protoc-gen-goweb