Merge branch 'fix_8403' of https://github.com/lrbabe/jquery into lrbabe-fix_8403

src/css.js

@@ -231,7 +231,8 @@ if ( !jQuery.support.opacity ) {
 		},
 
 		set: function( elem, value ) {
-			var style = elem.style;
+			var style = elem.style,
+				currentStyle = elem.currentStyle;
 
 			// IE has trouble with opacity if it does not have layout
 			// Force it by setting the zoom level
@@ -241,11 +242,11 @@ if ( !jQuery.support.opacity ) {
 			var opacity = jQuery.isNaN(value) ?
 				"" :
 				"alpha(opacity=" + value * 100 + ")",
-				filter = style.filter || "";
+				filter = currentStyle && currentStyle.filter || style.filter || "";
 
 			style.filter = ralpha.test(filter) ?
 				filter.replace(ralpha, opacity) :
-				style.filter + ' ' + opacity;
+				filter + " " + opacity;
 		}
 	};
 }

test/data/testsuite.css

 /* for testing opacity set in styles in IE */
-ol#empty { opacity: 0; filter:Alpha(opacity=0); }
+ol#empty { opacity: 0; filter:Alpha(opacity=0) progid:DXImageTransform.Microsoft.gradient(startColorStr='#ffff0000', EndColorStr='#ffffffff'); }
 
 div#fx-tests h4 {
         background: red;

test/unit/css.js

 module("css", { teardown: moduleTeardown });
 
 test("css(String|Hash)", function() {
-	expect(41);
+	expect( 42 );
 
 	equals( jQuery('#main').css("display"), 'block', 'Check for css property "display"');
 
@@ -58,6 +58,9 @@ test("css(String|Hash)", function() {
 	equals( jQuery('#empty').css('opacity'), '0', "Assert opacity is accessible via filter property set in stylesheet in IE" );
 	jQuery('#empty').css({ opacity: '1' });
 	equals( jQuery('#empty').css('opacity'), '1', "Assert opacity is taken from style attribute when set vs stylesheet in IE with filters" );
+	jQuery.support.opacity ?
+		ok(true, "Requires the same number of tests"):
+		ok( ~jQuery("#empty")[0].currentStyle.filter.indexOf("gradient"), "Assert setting opacity doesn't overwrite other filters of the stylesheet in IE" );
 
 	var div = jQuery('#nothiddendiv'), child = jQuery('#nothiddendivchild');