Make a feature detect for the attribute selected code. Fixes #5702.

src/attributes.js

@@ -261,16 +261,19 @@ jQuery.extend({
 		// Only do all the following if this is a node (faster for style)
 		if ( elem.nodeType === 1 ) {
 			// These attributes require special treatment
-			var special = rspecialurl.test( name ), parent = elem.parentNode;
+			var special = rspecialurl.test( name );
 
 			// Safari mis-reports the default selected property of an option
 			// Accessing the parent's selectedIndex property fixes it
-			if ( name === "selected" && parent ) {
-				parent.selectedIndex;
-
-				// Make sure that it also works with optgroups, see #5701
-				if ( parent.parentNode ) {
-					parent.parentNode.selectedIndex;
+			if ( name === "selected" && !jQuery.support.optSelected ) {
+				var parent = elem.parentNode;
+				if ( parent ) {
+					parent.selectedIndex;
+
+					// Make sure that it also works with optgroups, see #5701
+					if ( parent.parentNode ) {
+						parent.parentNode.selectedIndex;
+					}
 				}
 			}
 

src/support.js

@@ -8,7 +8,7 @@
 		id = "script" + now();
 
 	div.style.display = "none";
-	div.innerHTML = "   <link/><table></table><a href='/a' style='color:red;float:left;opacity:.55;'>a</a><select><option>text</option></select><input type='checkbox'/>";
+	div.innerHTML = "   <link/><table></table><a href='/a' style='color:red;float:left;opacity:.55;'>a</a><input type='checkbox'/>";
 
 	var all = div.getElementsByTagName("*"),
 		a = div.getElementsByTagName("a")[0];
@@ -52,6 +52,10 @@
 		// (WebKit defaults to "" instead)
 		checkOn: div.getElementsByTagName("input")[0].value === "on",
 
+		// Make sure that a selected-by-default option has a working selected property.
+		// (WebKit defaults to false instead of true, IE too, if it's in an optgroup)
+		optSelected: document.createElement("select").appendChild( document.createElement("option") ).selected,
+
 		// Will be defined later
 		scriptEval: false,
 		noCloneEvent: true,