Merge pull request #1779 from edx/talbs/fix-studio-notificationsie

Studio: FIX - correcting hiding state of notification UI for < IE9

cms/static/sass/contexts/_ie.scss

@@ -10,6 +10,10 @@
     &.is-shown {
       bottom: 0;
     }
+
+    &.is-hiding {
+      bottom: -($ui-notification-height);
+    }
   }
 }