`Node#setHTML()` on a `select` element, resolves #1023

This issue is being discussed here: https://github.com/yui/yui3/issues/1023

TL;DR: `appendChild`'ing a fragment to a `select` element causes the `selectedIndex` property to default to the last element in the fragment, which is wrong. This occurs in latest Firefox only.

@msweeney: Thoughts on my fix?