goprotobuf: Track file and message indexes, and reserve Descriptor as a message method name.
goprotobuf: Track file and message indexes, and reserve Descriptor as a message method name.

R=r
CC=golang-dev
http://codereview.appspot.com/6568051

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