IE bug: non-native listbox always showing the "No results." notice

[dgervalle]

IE does not support childElementCount on document fragment (see https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10060579/), causing the test on line 2038 to always fail. Highlight first selected option with test on line 258, should also fail due to the same issue (untested).

Here is a polyfill for that issue: https://developer.mozilla.org/en-US/docs/Web/API/ParentNode/childElementCount#Polyfill_for_IE8_IE9_Safari