allow to execute a part of the module graph at build time
e. g. to generate code or other assets
loaders have access to that via `this.importModule(request, options)`
get rid of startupNoDefault and many custom logic regarding this in jsonp chunk loading
add onChunksLoaded runtime method to cover that for all chunk loading types
add `__webpack_runtime_id__` to access the current runtime
allow to use onChunksLoaded for other module types too
Tobias Koppers