fix(ngClass): keep track of old ngClass value manually

ngClassWatchAction, when called as a $watch function, gets the wrong old
value after it has been invoked previously due to observation of the
interpolated class attribute. As a result it doesn't remove classes
properly. Keeping track of the old value manually seems to fix this.

Closes #1637

1 files changed, 3 insertions, 1 deletions

diff --git a/src/ng/directive/ngClass.js b/src/ng/directive/ngClass.js
index 79c55d7a..d731118f 100644
--- a/src/ng/directive/ngClass.js
+++ b/src/ng/directive/ngClass.js
@@ -3,6 +3,7 @@
 function classDirective(name, selector) {
   name = 'ngClass' + name;
   return ngDirective(function(scope, element, attr) {
+    var oldVal = undefined;
 
     scope.$watch(attr[name], ngClassWatchAction, true);
 
@@ -26,13 +27,14 @@ function classDirective(name, selector) {
     }
 
 
-    function ngClassWatchAction(newVal, oldVal) {
+    function ngClassWatchAction(newVal) {
       if (selector === true || scope.$index % 2 === selector) {
         if (oldVal && (newVal !== oldVal)) {
           removeClass(oldVal);
         }
         addClass(newVal);
       }
+      oldVal = newVal;
     }