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. This doesn't impact the functionality of the select,
but it can be problematic if option elements are selected with `option[selected]` in tests.

Closes #14115
Closes #14125

Author: Narretz

src/ng/directive/ngOptions.js

@@ -468,14 +468,20 @@ 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();