Make .attr(name, null) equivalent to removeAttr(name). (Was roughly t…

…his before - but is now consistent across platforms). Fixes #6341.

src/attributes.js

@@ -295,7 +295,14 @@ jQuery.extend({
 						jQuery.error( "type property can't be changed" );
 					}
 
-					elem[ name ] = value;
+					if ( value === null ) {
+						if ( elem.nodeType === 1 ) {
+							elem.removeAttribute( name );
+						}
+
+					} else {
+						elem[ name ] = value;
+					}
 				}
 
 				// browsers index elements by id/name on forms, give priority to attributes.

test/unit/attributes.js

@@ -98,22 +98,27 @@ test("attr(Hash)", function() {
 });
 
 test("attr(String, Object)", function() {
-	expect(23);
+	expect(24);
+
 	var div = jQuery("div").attr("foo", "bar"),
 		fail = false;
+
 	for ( var i = 0; i < div.size(); i++ ) {
 		if ( div.get(i).getAttribute('foo') != "bar" ){
 			fail = i;
 			break;
 		}
 	}
+
 	equals( fail, false, "Set Attribute, the #"+fail+" element didn't get the attribute 'foo'" );
 
 	// Fails on IE since recent changes to .attr()
 	// ok( jQuery("#foo").attr({"width": null}), "Try to set an attribute to nothing" );
 
 	jQuery("#name").attr('name', 'something');
 	equals( jQuery("#name").attr('name'), 'something', 'Set name attribute' );
+	jQuery("#name").attr('name', null);
+	equals( jQuery("#name").attr('title'), '', 'Remove name attribute' );
 	jQuery("#check2").attr('checked', true);
 	equals( document.getElementById('check2').checked, true, 'Set checked attribute' );
 	jQuery("#check2").attr('checked', false);