Files generated by webpack and friends are compiled files. You have to upload the source you generated your extension from to AMO for review of a listed extension. This will mean that your extension has to be reviewed by an admin-reviewer, which will result in a longer wait time in queue.
If you are ok with that trade-off there are a few measures you can take to make the review easier:
- Don't minify the generated code (UglifyJsPlugin for webpack)
- Don't use loaders that transform the JS output (like babel or similar)
- Don't include third-party libraries in your file, instead directly use the original source file
- Use a commons chunk or equivalent if possible for shared code