Permissions are now saved in the Role configuration entity they have been granted for.

Previously, role permission assignments were stored in a {role_permissions} table in the database. Instead, we are now storing the permissions of a role directly on the Role configuration entity(see User roles are now configurables).

Instead of using procedural wrappers you can now retrieve or manipulate a role's permission through a set of methods defined in the RoleInterface.

Drupal 7

// Retrieving a list of granted permissions for a role
$permissions = user_role_permissions($rids);

// Checking if a role has a permission.
$permissions = user_role_permissions($rids);
isset($permissions[$rid]['access content']);

// Granting permissions.
user_role_grant_permissions($rid, array('access content', 'post comments'));

// Revoking permissions.
user_role_revoke_permissions($rid, array('access content'));

Drupal 8

// Retrieving a list of granted permissions for a role
$role->getPermissions();

// Checking if a role has a permission.
$role->hasPermission('access content');

// Granting permissions.
$role->grantPermission('post comments');

// Revoking permissions.
$role->revokePermission('access content');