fix(ngAria): remove tabindex from radio buttons

Closes #12492

Author: marcysutton

Diff for: src/ngAria/aria.js

@@ -235,7 +235,8 @@ ngAriaModule.directive('ngShow', ['$aria', function($aria) {
           }
         },
         post: function(scope, elem, attr, ngModel) {
-          var needsTabIndex = shouldAttachAttr('tabindex', 'tabindex', elem);
+          var needsTabIndex = shouldAttachAttr('tabindex', 'tabindex', elem)
+                                && !isNodeOneOf(elem, nodeBlackList);
 
           function ngAriaWatchModelValue() {
             return ngModel.$modelValue;

Diff for: test/ngAria/ariaSpec.js

@@ -628,6 +628,13 @@ describe('$aria', function() {
       expectAriaAttrOnEachElement(element, 'tabindex', undefined);
     });
 
+    it('should not attach to native controls via ngmodel', function() {
+      scope.$apply('val = null');
+      compileElement('<input type="radio" name="value" value="1" ng-model="val">');
+
+      expect(element.attr('tabindex')).toBeUndefined();
+    });
+
     it('should not attach to random ng-model elements', function() {
       compileElement('<div ng-model="val"></div>');
       expect(element.attr('tabindex')).toBeUndefined();