Fixed #2076 where .val() could return an array instead of undefined when the...

Fixed #2076 where .val() could return an array instead of undefined when the jquery object was empty.  The bug was created during the .val() refactoring for the javascript strict FF ticket.

src/core.js

@@ -419,6 +419,7 @@ jQuery.fn = jQuery.prototype = {
 
 			}
 
+			return undefined;
 		}
 
 		return this.each(function(){

test/unit/core.js

@@ -1029,11 +1029,12 @@ test("$.extend(Object, Object)", function() {
 });
 
 test("val()", function() {
-	expect(3);
+	expect(4);
 	ok( $("#text1").val() == "Test", "Check for value of input element" );
 	ok( !$("#text1").val() == "", "Check for value of input element" );
 	// ticket #1714 this caused a JS error in IE
 	ok( $("#first").val() == "", "Check a paragraph element to see if it has a value" );
+	ok( $([]).val() === undefined, "Check an empty jQuery object will return undefined from val" );
 });
 
 test("val(String)", function() {