fix(menu): fix memory leak on component destroy

Closes #3775.

Author: isyun

src/components/menu/_menu.js

@@ -167,10 +167,8 @@ function MenuDirective($mdMenu) {
     mdMenuCtrl.init(menuContainer);
 
     scope.$on('$destroy', function() {
-      if (mdMenuCtrl.isOpen) {
-        menuContainer.remove();
-        mdMenuCtrl.close();
-      }
+      menuContainer.remove();
+      mdMenuCtrl.close();
     });
 
   }
@@ -207,6 +205,8 @@ function MenuController($mdMenu, $attrs, $element, $scope) {
 
   // Use the $mdMenu interim element service to close the menu contents
   this.close = function closeMenu(skipFocus) {
+    if ( !ctrl.isOpen ) return;
+
     ctrl.isOpen = false;
     triggerElement.setAttribute('aria-expanded', 'false');
     $mdMenu.hide();