I suspect HMR does not working properly on dev because we have multiple entries.
One relative issue: https://github.com/webpack/webpack-dev-server/issues/2792/
I think we do not need multiple entries for polyfills & plugins after all. They could be in the same chunk, and could be later optimized through splitChunks option.
`ses.ts` is changed to `ses-lockdown.ts` because `ses.ts` does not pass circular dependency check by madge. I haven't looked through the real root cause though. See https://github.com/pahen/madge/issues/355
