Use textContent instead of innerText when possible

innerText is an IE thing. textContent is supported on all modern versions of major browsers.
More information: https://developer.mozilla.org/en-US/docs/Web/API/Node.textContent

This fix will also (hopefully, as I don't have any machine where IE is older than 9 to test) fallback to innerText on older versions  of IE.

Fixes issue #2