Merge branch 'master' of github.com:jquery/jquery

1 files changed, 8 insertions, 3 deletions

diff --git a/src/traversing.js b/src/traversing.js
index fb5946bba..e0f40151d 100644
--- a/src/traversing.js
+++ b/src/traversing.js
@@ -73,9 +73,9 @@ jQuery.fn.extend({
 	},
 
 	is: function( selector ) {
-		return !!selector && (typeof selector === "string" ?
+		return !!selector && ( typeof selector === "string" ?
 			jQuery.filter( selector, this ).length > 0 :
-			this.filter( selector ).length > 0);
+			this.filter( selector ).length > 0 );
 	},
 
 	closest: function( selectors, context ) {
@@ -298,13 +298,18 @@ jQuery.extend({
 
 // Implement the identical functionality for filter and not
 function winnow( elements, qualifier, keep ) {
+
+	// Can't pass null or undefined to indexOf in Firefox 4
+	// Set to 0 to skip string check
+	qualifier = qualifier || 0;
+
 	if ( jQuery.isFunction( qualifier ) ) {
 		return jQuery.grep(elements, function( elem, i ) {
 			var retVal = !!qualifier.call( elem, i, elem );
 			return retVal === keep;
 		});
 
-	} else if ( qualifier && qualifier.nodeType ) {
+	} else if ( qualifier.nodeType ) {
 		return jQuery.grep(elements, function( elem, i ) {
 			return (elem === qualifier) === keep;
 		});