fix(select): placeholder (empty option) is lost in IE9

src/ng/directive/select.js

@@ -468,7 +468,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                 if (existingOption.id !== option.id) {
                   lastElement.val(existingOption.id = option.id);
                 }
-                if (existingOption.element.selected !== option.selected) {
+                if (!!lastElement.selected !== option.selected) {
                   lastElement.prop('selected', (existingOption.selected = option.selected));
                 }
               } else {

test/ng/directive/selectSpec.js

@@ -977,6 +977,19 @@ describe('select', function() {
         expect(option.attr('id')).toBe('road-runner');
         expect(option.attr('custom-attr')).toBe('custom-attr');
       });
+
+      it ('should select the null option, if it\'s available and no other option is selected', inject(function($timeout) {
+        // selectedIndex is used here because jqLite incorrectly reports element.val()
+        scope.$apply(function() {
+          scope.values = [{name: 'A'}];
+        });
+        createSingleSelect(true);
+        // ensure the first option (the null option) is selected
+        expect(element[0].selectedIndex).toEqual(0);
+        scope.$digest();
+        // ensure the option has not changed following the digest
+        expect(element[0].selectedIndex).toEqual(0);
+      }));
     });