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` attribute too.

Closes #9621

Author: petebacondarwin

src/ng/directive/select.js

@@ -623,6 +623,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                   updateLabelMap(labelMap, existingOption.label, false);
                   updateLabelMap(labelMap, option.label, true);
                   lastElement.text(existingOption.label = option.label);
+                  msie && lastElement.attr('label', existingOption.label);
                 }
                 if (existingOption.id !== option.id) {
                   lastElement.val(existingOption.id = option.id);
@@ -653,6 +654,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
                       .prop('selected', option.selected)
                       .attr('selected', option.selected)
                       .text(option.label);
+                  msie && element.attr('label', option.label);
                 }
 
                 existingOptions.push(existingOption = {

test/ng/directive/selectSpec.js

@@ -1320,6 +1320,25 @@ describe('select', function() {
       expect(scope.selected).toBe(scope.values[0]);
     });
 
+    // bug fix #9621
+    if (msie) {
+      it('should update the label attribute if running in MS IE', 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).attr('label')).toEqual('A');
+        expect(options.eq(1).attr('label')).toEqual('B');
+        expect(options.eq(2).attr('label')).toEqual('C');
+      });
+    }
+
     describe('binding', function() {
 
       it('should bind to scope value', function() {