Remove dependencies on polyfills?

[justinfagnani]

In relatively recent versions of Node, including the current LTS, object-assign and nodegit-promise are unnecessary. It'd be great if promisify-node didn't directly depend on polyfill (or polyfill-like in the case of object-assign) libraries and instead required that the environment provide them if necessary.

[maxkorp]

nodegit-promise is not unnecessary. it has custom promise implementation that allows us to synchronously poll it's state in C++, which is not available with the built in promise implementation.
Object assign probably yeah, although how long has that been in? We're staying supporting node 4 since it's LTS.

[heyimalex]

FYI, Object.assign is definitely in node v4. Check out node.green for a decent feature support table.