Fix #14101: $().data() should be undefined, not null

src/data.js

@@ -75,8 +75,7 @@ jQuery.extend({
 
 jQuery.fn.extend({
 	data: function( key, value ) {
-		var i, name,
-			data = null,
+		var i, name, data,
 			elem = this[ 0 ],
 			attrs = elem && elem.attributes;
 

test/unit/data.js

@@ -170,6 +170,12 @@ test("jQuery.data(object/flash)", 25, function() {
 	dataTests( flash );
 });
 
+// attempting to access the data of an undefined jQuery element should be undefined
+test("jQuery().data() === undefined (#14101)", 2, function() {
+	strictEqual(jQuery().data(), undefined);
+	strictEqual(jQuery().data("key"), undefined);
+});
+
 test(".data()", function() {
 	expect(5);