fix(autocomplete): prevent flashing of invalid state (#12064)

- when user clicks on suggestion, input element lost focus and then programmatically get focused
- again, add stop immediate propagation to prevent blur event handling by other handlers which
- update ng-model validity state
- add check that the event is an object

Fixes #10975

Author: shishkinilya

src/components/autocomplete/js/autocompleteController.js

@@ -598,13 +598,16 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $mdTheming,
 
   /**
    * Handles input blur event, determines if the dropdown should hide.
+   * @param {Event=} $event
    */
   function blur($event) {
     hasFocus = false;
 
     if (!noBlur) {
       ctrl.hidden = shouldHide();
       evalAttr('ngBlur', { $event: $event });
+    } else if (angular.isObject($event)) {
+      $event.stopImmediatePropagation();
     }
   }