Safari 11.1 re AbortController & AbortSignal

It's broken in Safari and was only fixed in 12.1. https://caniuse.com/abortcontroller

We can feature detect it by doing new Request(location.href).signal !== undefined or Request.prototype.hasOwnProperty('signal') !== false

Should we require Safari 12.1?

changed the description

ok, we'll drop it using feature detection. Needs some quick testing for firefox 68/chrome to be sure.

closed with commit ec96bb8a

Tested on browserstack with various devices. Looks like iOS 13 is required.. Let's see if there are any complains. I don't see any old iOS devices in the analytics at least.

mentioned in commit ec96bb8a

mentioned in issue #28 (closed)