I'd look into a different way of retrieving the property, personally.
If you look at the DOM in both Chrome and IE9, it's the same - it seems that the problem (surprise, surprise) is with jQuery. It's returning dodgy information...
IE:
<input style="width: 100%; padding-right: 0px; padding-left: 4px; font-weight: bold;" id="ctl00_ebtnSearch_input"></input>
Chrome:
<input class="rbDecorated" type="submit" name="ctl00$ebtnSearch" id="ctl00_ebtnSearch_input" value=" Search " style="font-weight:bold;width:100%;padding-left:0;padding-right:0;padding-left:4px;"></input>
In fact, this returns "" in both browsers:
document.getElementById('ctl00_ebtnSearch_input').style.background
Which is entirely reasonable, given that clearly from the DOM, there is no inline style (or one applied through javascript) that affects .style.background - or any of background's attributes.
What are you trying to get, and for what purpose? Perhaps there's another solution that's not been considered..