Headers.prototype.getAll() is removed from the Fetch API specification.
Docs: https://github.com/whatwg/fetch/commit/42464c https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/x3YXciXQWM0 https://developer.mozilla.org/en-US/docs/Web/API/Headers https://developer.mozilla.org/en-US/docs/Web/API/Headers/getAll