Request: Separate libraries per proto file (even though one imports the other)

How do I properly generate JS stubs for A.proto that imports B.proto, where there is already a client library generated for B.proto? What I would basically want is that both .proto files have their own generated JS library and I can just install both in a JS project separately.

I have two projects with a .proto file, and one imports the other. Both projects are maintained and compiled separately. The setup is as follows:

```
domain project:
|-- company
`-- domain
`-- domain.proto

service project:
|-- company
`-- service
`-- service.proto
```

```
// domain.proto
syntax = "proto3";

message User {
string name = 1;
}
```

```
// service.proto
syntax = "proto3";

import company/domain/domain.proto

message Ping {
domain.User user = 1;
}
```
I can compile `company/service/service.proto` using `protoc /company/service/service.proto` but the resulting .js file tries to import from a folder in the same (npm) project:

```
var company_domain_domain_pb = require('../../company/domain/domain_pb.js');
```
But `domain` is installed as a separate npm package. Somehow it seems that I have to compile both `.proto` files at once for grpc-web to set the path correctly. This differs from the Python grpc compiler which generates separate libraries that I can `pip install` separately. I just have to make sure to import both libraries in the Python case. I would expect something similar with the JavaScript compiler.

As can be read [here](https://groups.google.com/forum/#!topic/grpc-io/GzKW3KZTnV4) this is not yet supported, that's why I'm posting this request here (as requested).