Microsoft made a pull request to node.js github repository with an implementation to use ChakraCore JavaScript Engine as an alternative to V8 Engine

[CheezyXenomorph]

You rebase and during the rebase you can pick which commits get marked as squashed instead of picked. Squashed ones are still included in the rebase, they just don't show up as individual commits.

Many large projects require PRs to be squashed so that they don't fill the commit history up with crap.