test(select): relax test for IE8 bug

There is a bug in IE8 (http://support.microsoft.com/kb/829907 and
http://yuilibrary.com/forum-archive/forum/viewtopic.php@p=14826.html):
when you clone an `<option>` element the selected attribute on the options
can become invalid.

This is not relevant to the proper behaviour of the `select` directive
since it uses `prop` not `attr` to store the selected status of each
option.

This test is only interested in there being at least on option with
the `selected` attribute, for conformance to accessibility guidelines.
So we can safely relax the test to check this rather than concerning
ourselves with which option actually has this attribute.

Fixes 79538afd7bd730d49be8eb988a3a54848d8ddaec
Closes #8465