Add cache context and cachable dependency.

Closes #3285735

src/Routing/ReorderChildrenAccess.php

@@ -81,14 +81,14 @@ class ReorderChildrenAccess implements AccessCheckInterface {
       if (!$entity) {
         // At this point we can't proceed so we err on the side of caution and
         // deny access to the tab.
-        return AccessResult::forbidden();
+        return AccessResult::forbidden()->addCacheableDependency($entity);
       }
     }
 
     if ($entity && $this->parentCandidate->getCandidateFields($entity)) {
-      return AccessResult::allowed()->setCacheMaxAge(0);
+      return AccessResult::allowed()->addCacheableDependency($entity);
     }
-    return AccessResult::forbidden();
+    return AccessResult::forbidden()->addCacheableDependency($entity);
   }
 
 }