fix "==" to "===" as per linter

Author: Thesoro

src/ng/directive/ngOptions.js

@@ -489,7 +489,7 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
 
         selectCtrl.readValue = function readNgOptionsValue() {
 
-          if (selectElement.val() == '') return $parse(attr.ngEmptyValue)(scope);
+          if (selectElement.val() === '') return $parse(attr.ngEmptyValue)(scope);
 
           var selectedOption = options.selectValueMap[selectElement.val()];