Fails to function if included at end of document

Is this a known issue? If html5shiv is included at the bottom of the document (as is normally advised for scripts), any elements already in the DOM are not fixed.

This holds true regardless where the shim is inserted: i.e. any HTML5 elements already in the DOM prior to the shim are not fixed (so they don't get styling).

If this is a known issue, I'll submit a PR to add a note to the readme about this.