saml2/sp/initSSO.php: Handle IsPassive parameter properly

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@1768 44740490-163a-0410-bde0-09ae8108e29a

www/saml2/sp/initSSO.php

@@ -99,7 +99,7 @@ try {
 	$ar->setRelayState($_REQUEST['RelayState']);
 
 	if (isset($_GET['IsPassive'])) {
-		$ar->setIsPassive($_GET['IsPassive']);
+		$ar->setIsPassive((bool)$_GET['IsPassive']);
 	}
 
 	/* Save request information. */