fix(select): invalidate when 'multiple`, `required` and model is `[]`

When `multiple` attribute is set on a `<select>` control and the model value is an empty array,
we should invalidate the control.  Previously, this directive was using incorrect logic for
determining if the model was empty.

Closes #5337

1 files changed, 3 insertions, 11 deletions

diff --git a/src/ng/directive/select.js b/src/ng/directive/select.js
index d87fa5d3..3dbb5b8e 100644
--- a/src/ng/directive/select.js
+++ b/src/ng/directive/select.js
@@ -221,18 +221,10 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
       selectCtrl.init(ngModelCtrl, nullOption, unknownOption);
 
       // required validator
-      if (multiple && (attr.required || attr.ngRequired)) {
-        var requiredValidator = function(value) {
-          ngModelCtrl.$setValidity('required', !attr.required || (value && value.length));
-          return value;
+      if (multiple) {
+        ngModelCtrl.$isEmpty = function(value) {
+          return !value || value.length === 0;
         };
-
-        ngModelCtrl.$parsers.push(requiredValidator);
-        ngModelCtrl.$formatters.unshift(requiredValidator);
-
-        attr.$observe('required', function() {
-          requiredValidator(ngModelCtrl.$viewValue);
-        });
       }
 
       if (optionsExp) setupAsOptions(scope, element, ngModelCtrl);