Revert "Revert "Make sure session is saved after changing (#1573)" (#1574)" (#1591)

This reverts commit 4355550.

Author: barryvdh

src/SymfonyHttpDriver.php

@@ -51,6 +51,7 @@ public function isSessionStarted()
     public function setSessionValue($name, $value)
     {
         $this->session->put($name, $value);
+        $this->saveSession();
     }
 
     /**
@@ -75,5 +76,12 @@ public function getSessionValue($name)
     public function deleteSessionValue($name)
     {
         $this->session->remove($name);
+        $this->saveSession();
+    }
+
+    protected function saveSession()
+    {
+        $this->session->reflash();
+        $this->session->save();
     }
 }