Non module css doesn't work with :local() in CRA 3.0

Created by: almyy

Is this a bug report?

Yes

Did you try recovering your dependencies?

Yes

Environment

Environment Info:

  System:
    OS: Linux 4.14 Manjaro Linux
    CPU: (12) x64 Intel(R) Core(TM) i9-8950HK CPU @ 2.90GHz
  Binaries:
    Node: 10.15.1 - ~/.nvm/versions/node/v10.15.1/bin/node
    Yarn: 1.15.2 - /usr/bin/yarn
    npm: 6.4.1 - ~/.nvm/versions/node/v10.15.1/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: Not Found
  npmPackages:
    react: ^16.8.6 => 16.8.6 
    react-dom: ^16.8.6 => 16.8.6 
    react-scripts: 3.0.0 => 3.0.0 
  npmGlobalPackages:
    create-react-app: Not Found

Steps to Reproduce

(Write your steps here:)

Have a non module css-file, e.g. MyStyle.css
Have a class in said file as a :local scoped class, e.g. :local(.myClass) { ... }
Import CSS file in a React-component, e.g. import css from './MyStyle.css'
Observe that the classname is not exported

Expected Behavior

That the css class has been given a random name and is available as a property on the css object, e.g. { myClass: "_2uhJkdnDbAceZ0gQC-r3vz" }

Actual Behavior

Object was empty: {}

Reproducible Demo

Source: https://github.com/almyy/local-classname-repro

Deployed example: https://almyy.github.io/local-classname-repro/