add ability to load dependent chunks for non-web targets

[sokra]

This allows to use splitChunks for initial chunks in i. e. node and webworker targets

fixes #8161

What kind of change does this PR introduce?
refactor, feature

Did you add tests for your changes?
yes

Does this PR introduce a breaking change?
yes, RuntimeGlobals.startup now works differently

What needs to be documented once your changes are merged?
nothing

[webpack-bot]

For maintainers only:

• This need to be documented (issue in webpack/webpack.js.org will be filed when merged)

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[russell-dot-js]

Hi @sokra,

I'm really excited about this feature because it allows me to build quickly (only tree-shake node_modules once) while minimizing artifact size (I version functions in AWS lambda and have hundreds deployed).

However, while digging in and starting to use it today, I found one issue. It works great, however it does not work with entries that have relative path.

E.g. if my vendor chunk is in /vendor.js, but my code is in /path/to/some/entry.js, entry.js will try to require('./vendor.js') rather than keeping the context of its relative path.

I THINK the right thing to do is to extend the functionality you've provided here, to be aware of relative path to dependent chunks, rather than naively requiring them.

What are your thoughts? Will this be a pretty easy change? TBH I haven't contributed to Webpack yet and get a little lost in the code