fix(ngOptionsDirective): fix form pristine (use !equals function instead of !== for issue 13211)

Author: m-amr

src/ng/directive/ngOptions.js

@@ -733,7 +733,8 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
         // Check to see if the value has changed due to the update to the options
         if (!ngModelCtrl.$isEmpty(previousValue)) {
           var nextValue = selectCtrl.readValue();
-          if (ngOptions.trackBy ? !equals(previousValue, nextValue) : previousValue !== nextValue) {
+          ngOptions.trackBy = !equals(previousValue, nextValue);
+          if (ngOptions.trackBy) {
             ngModelCtrl.$setViewValue(nextValue);
             ngModelCtrl.$render();
           }