EmulateIE9 is not a valid X-UA-Compatible flag. Moreover there can only be one X-UA-Compatible flag at all. ( http://msdn.microsoft.com/en-us/library/cc288325(v=VS.85).aspx ). The EmulateIE7 mode was introduced for a special reason, that is to allow sites with mixed Quirks mode (IE5 stds) and newer (IE7 stds) to work properly. It will use the normal IE document mode compatibility methods to determine what mode to apply and then use either Quirks or IE7 standards.
However, what is wanted here is neither. Instead I would suggest a change to the following header:
<!--[if IE 8]>
<meta http-equiv="X-UA-Compatible" content="IE=7">
Like that it will only affect IE 8 (which is affected) and will also use the intended IE7 standards without having to decide any further there.