fix(menu): all menus no longer self destruct when one is destroyed

closes #5395

Author: rschmukler

src/components/menu/js/menuController.js

@@ -7,7 +7,7 @@ angular
 /**
  * @ngInject
  */
-function MenuController($mdMenu, $attrs, $element, $scope, $mdUtil, $timeout, $rootScope) {
+function MenuController($mdMenu, $attrs, $element, $scope, $mdUtil, $timeout, $rootScope, $q) {
 
   var menuContainer;
   var self = this;
@@ -149,7 +149,7 @@ function MenuController($mdMenu, $attrs, $element, $scope, $mdUtil, $timeout, $r
   };
 
   this.destroy = function() {
-    return $mdMenu.destroy();
+    return self.isOpen ? $mdMenu.destroy() : $q.when(false);
   };
 
   // Use the $mdMenu interim element service to close the menu contents