[FrameworkBundle] Make the security context optional

src/Symfony/Bundle/FrameworkBundle/Resources/config/templating.xml

@@ -108,7 +108,7 @@
 
         <service id="templating.helper.security" class="%templating.helper.security.class%">
             <tag name="templating.helper" alias="security" />
-            <argument type="service" id="security.context" />
+            <argument type="service" id="security.context" on-invalid="ignore" />
         </service>
 
         <service id="templating.form" class="%templating.form.class%">

src/Symfony/Bundle/FrameworkBundle/Templating/Helper/SecurityHelper.php

@@ -28,7 +28,7 @@ class SecurityHelper extends Helper
      *
      * @param SecurityContext $context A SecurityContext instance
      */
-    public function __construct(SecurityContext $context)
+    public function __construct(SecurityContext $context = null)
     {
         $this->context = $context;
     }