Generating bundles for several targets at once

It would be useful to generate bundles for several targets at once.

I need this to generate bundles both for web and node targets, one is to send to a browser, another is to evaluate in Node to pre-render UI on server (with React).

Reasons why generating them at once could be useful:

• Shared cache, increa
• Shared watchers

These two will lead to less work done by webpack and so compilation should be faster and allocate less resources (memory, fds).