fix(select): ensure the label attribute is updated in Internet Explorer

Only changing the `<option>` text value is not enough to trigger a render
change in IE. We need to explicit update the `label` property too.

Closes #9621
Closes #10042

Author: petebacondarwin

src/ng/directive/select.js

@@ -551,6 +551,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                 lastElement = existingOption.element;
                 if (existingOption.label !== option.label) {
                   lastElement.text(existingOption.label = option.label);
+                  lastElement.prop('label', existingOption.label);
                 }
                 if (existingOption.id !== option.id) {
                   lastElement.val(existingOption.id = option.id);
@@ -580,6 +581,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                       .val(option.id)
                       .prop('selected', option.selected)
                       .attr('selected', option.selected)
+                      .prop('label', option.label)
                       .text(option.label);
                 }
 

test/ng/directive/selectSpec.js

@@ -847,6 +847,23 @@ describe('select', function() {
       expect(scope.selected).toBe(scope.values[0]);
     });
 
+    // bug fix #9621
+    it('should update the label property', function() {
+      // ng-options="value.name for value in values"
+      // ng-model="selected"
+      createSingleSelect();
+
+      scope.$apply(function() {
+        scope.values = [{name: 'A'}, {name: 'B'}, {name: 'C'}];
+        scope.selected = scope.values[0];
+      });
+
+      var options = element.find('option');
+      expect(options.eq(0).prop('label')).toEqual('A');
+      expect(options.eq(1).prop('label')).toEqual('B');
+      expect(options.eq(2).prop('label')).toEqual('C');
+    });
+
     describe('binding', function() {
 
       it('should bind to scope value', function() {