fix(ngOptions): always set the 'selected' attribute for selected options

We don't set selected property / attribute on options that are already selected.
That happens for example if the browser has automatically selected the first
option in a select. In that case, the selected property is set automatically, but
the selected attribute is not

Closes #14115

Author: Narretz

src/ng/directive/ngOptions.js

@@ -472,14 +472,20 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
           var option = options.getOptionFromViewValue(value);
 
           if (option && !option.disabled) {
+            // Don't update the option when it is already selected.
+            // For example, the browser will select the first option by default. In that case,
+            // most properties are set automatically - except the `selected` attribute, which we
+            // set always
+
             if (selectElement[0].value !== option.selectValue) {
               removeUnknownOption();
               removeEmptyOption();
 
               selectElement[0].value = option.selectValue;
               option.element.selected = true;
-              option.element.setAttribute('selected', 'selected');
             }
+
+            option.element.setAttribute('selected', 'selected');
           } else {
             if (value === null || providedEmptyOption) {
               removeUnknownOption();

test/ng/directive/ngOptionsSpec.js

@@ -298,6 +298,40 @@ describe('ngOptions', function() {
 
   });
 
+  it('should set the "selected" attribute and property on selected options', function() {
+    scope.values = [{
+      id: 'FF0000',
+      display: 'red'
+    }, {
+      id: '0000FF',
+      display: 'blue'
+    }];
+    scope.selected = 'FF0000';
+
+    createSelect({
+      'ng-model': 'selected',
+      'ng-options': 'option.id as option.display for option in values'
+    });
+    scope.$digest();
+
+    var options = element.find('option');
+    expect(options.length).toEqual(2);
+    expect(options.eq(0)).toEqualOption('FF0000', 'red');
+    expect(options.eq(1)).toEqualOption('0000FF', 'blue');
+
+    expect(options.eq(0)[0].getAttribute('selected')).toBe('selected');
+    expect(options.eq(0).attr('selected')).toBe('selected');
+    expect(options.eq(0)[0].selected).toBe(true);
+    expect(options.eq(0).prop('selected')).toBe(true);
+
+    scope.selected = '0000FF';
+    scope.$digest();
+
+    expect(options.eq(1)[0].getAttribute('selected')).toBe('selected');
+    expect(options.eq(1).attr('selected')).toBe('selected');
+    expect(options.eq(1)[0].selected).toBe(true);
+    expect(options.eq(1).prop('selected')).toBe(true);
+  });
 
   it('should render zero as a valid display value', function() {
     createSingleSelect();