IE 9 preserves the case of the Alpha filter - maintain it in the test as well.

test/unit/css.js

@@ -145,7 +145,7 @@ if(jQuery.browser.msie) {
   	equals( jQuery('#foo').css('opacity'), '1', "Assert opacity is 1 when a different filter is set in IE, #1438" );
 
     var filterVal = "progid:DXImageTransform.Microsoft.Alpha(opacity=30) progid:DXImageTransform.Microsoft.Blur(pixelradius=5)";
-    var filterVal2 = "progid:DXImageTransform.Microsoft.alpha(opacity=100) progid:DXImageTransform.Microsoft.Blur(pixelradius=5)";
+    var filterVal2 = "progid:DXImageTransform.Microsoft.Alpha(opacity=100) progid:DXImageTransform.Microsoft.Blur(pixelradius=5)";
     var filterVal3 = "progid:DXImageTransform.Microsoft.Blur(pixelradius=5)";
     jQuery('#foo').css("filter", filterVal);
     equals( jQuery('#foo').css("filter"), filterVal, "css('filter', val) works" );
@@ -300,4 +300,4 @@ test(":visible selector works properly on children with a hidden parent (bug #45
 	expect(1);
 	jQuery('#table').css('display', 'none').html('<tr><td>cell</td><td>cell</td></tr>');
 	equals(jQuery('#table td:visible').length, 0, "hidden cell children not perceived as visible");
-});
+});
\ No newline at end of file