fix(select): avoid checking option element selected properties in render

In Firefox, hovering over an option in an open select menu updates the selected property of option
elements. This means that when a render is triggered by the digest cycle, and the list of options
is being rendered, the selected properties are reset to the values from the model and the option
hovered over changes. This fix changes the code to only use DOM elements' selected properties in a
comparison when a change event has been fired. Otherwise, the internal new and existing option
arrays are used.

Closes angular#2448

src/ng/directive/select.js

@@ -322,7 +322,8 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
             // We try to reuse these if possible
             // - optionGroupsCache[0] is the options with no option group
             // - optionGroupsCache[?][0] is the parent: either the SELECT or OPTGROUP element
-            optionGroupsCache = [[{element: selectElement, label:''}]];
+            optionGroupsCache = [[{element: selectElement, label:''}]],
+            changeEventFired = false;
 
         if (nullOption) {
           // compile the element since there might be bindings in it
@@ -341,6 +342,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
         selectElement.empty();
 
         selectElement.on('change', function() {
+          changeEventFired = true;
           scope.$apply(function() {
             var optionGroup,
                 collection = valuesFn(scope) || [],
@@ -529,7 +531,10 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                   lastElement.val(existingOption.id = option.id);
                 }
                 // lastElement.prop('selected') provided by jQuery has side-effects
-                if (lastElement[0].selected !== option.selected) {
+                // FF will update selected property on DOM elements when hovering,
+                // so we shouldn't check those unless a change event has happened
+                if ((changeEventFired && lastElement[0].selected !== option.selected) ||
+                  existingOption.selected !== option.selected) {
                   lastElement.prop('selected', (existingOption.selected = option.selected));
                 }
               } else {
@@ -573,6 +578,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
           while(optionGroupsCache.length > groupIndex) {
             optionGroupsCache.pop()[0].element.remove();
           }
+          changeEventFired = false;
         }
       }
     }

test/ng/directive/selectSpec.js

@@ -733,6 +733,21 @@ describe('select', function() {
       expect(sortedHtml(options[2])).toEqual('<option value="1">3</option>');
     });
 
+    it('should ignore option object selected changes', function() {
+      createSingleSelect();
+
+      scope.$apply(function() {
+        scope.values = [{name: 'A'}, {name: 'B'}, {name: 'C'}];
+        scope.selected = scope.values[0];
+      });
+
+      var options = element.find('option');
+      var optionToSelect = options.eq(1);
+      optionToSelect.prop('selected', true);
+      scope.$digest();
+      expect(optionToSelect.prop('selected')).toBe(true);
+    });
+
     describe('binding', function() {
 
       it('should bind to scope value', function() {