Baseline of <select> elements

Hi there,

this may or may not be appropriate for this mailing list, but since I'm
starting out with a CSS question I'll start here.

According to http://www.w3.org/TR/CSS2/visudet.html#propdef-vertical-align:
"The baseline of an 'inline-block' is the baseline of its last line box in
the normal flow, unless it has either no in-flow line boxes or if its
'overflow' property has a computed value other than 'visible', in which
case the baseline is the bottom margin edge."

Now, a <select> element behaves a lot like an inline-block element, and UA
default stylesheets make it one, though I guess it's technically a replaced
element. Still, my question here is, what should be the baseline for a
<select> that has a style of overflow: hidden as seen on
http://panasonic.asia/in/airconditioner/EnergySavingCalculator.html (the
select next to SELECT YOUR HOME TYPE)

Simplified testcase at http://jsbin.com/qosewufema/1/

IE and Firefox calculate the baseline ignoring the overflow: hidden. Blink
currently notices the overflow: hidden and calculates the baseline as the
bottom of the margin edge. Who is right?

-christian