Apply mixin to correct class

dist/css/bootstrap.css

@@ -3352,9 +3352,11 @@ button.close {
     float: left !important;
   }
   .navbar-right {
+    float: right !important;
+  }
+  .navbar-right .dropdown-menu {
     right: 0;
     left: auto;
-    float: right !important;
   }
 }
 

less/navbar.less

@@ -261,7 +261,9 @@
   .navbar-left  { .pull-left(); }
   .navbar-right {
     .pull-right();
-    .pull-right > .dropdown-menu();
+    .dropdown-menu {
+      .pull-right > .dropdown-menu();
+    }
   }
 }