…rators in Node 12 (#1172)

* fix: premature close with chunked transfer encoding and for async iterators in Node 12

This PR backports the fix from #1064 to the `2.x.x` branch following
the [comment here](#1064 (comment)).

I had to add some extra babel config to allow using the `for await..of`
syntax in the tests.  The config is only needed for the tests as
this syntax is not used in the implementation.

* chore: fix up tests for node 6+

* chore: codecov dropped support for node < 8 without shipping major

* chore: npm7 strips empty dependencies hash during install

* chore: pin deps to versions that work on node 4

* chore: do not emit close error after aborting a request

* chore: test on node 4-16

* chore: simplify chunked transer encoding bad ending

* chore: avoid calling .destroy as it is not in every node.js release

* chore: listen for response close as socket is reused and shows warnings

backport for #1599 to the 2.x branch

Co-authored-by: Guilherme Victal <guilherme.a@dasa.com.br>

…js` (#1534)

Because of JS hoisting `var global` to the top of the file, `typeof
global` in `getGlobal()` will always be `undefined`.

By using a different variable name like `globalObject`, we are able to
read the "real" `typeof global` and get access to the global object that
way.