Generator redeclares same function name when given a proto with multiple services

When give `.proto` file of such
```
...
service FirstService {
rpc List (ObjectA) returns (ObjectA) {}
}

service SecondService {
rpc List (ObjectB) returns (ObjectB) {}
}
```

The `protoc` generator will generate the following stub using `mode=grpcwebtext`

```
...
const methodInfo_List = new grpc.web.AbstractClientBase.MethodInfo(
proto.servicename.ObjectB,
...
);

// and another one with the same name
const methodInfo_List = new grpc.web.AbstractClientBase.MethodInfo(
proto.servicename.ObjectA,
...
);
```

which results in a `SyntaxError`