Remove unused local variables in tests

Author: fancyweb

Tests/CookieTest.php

@@ -198,6 +198,6 @@ public function testConstructException()
     {
         $this->expectException('UnexpectedValueException');
         $this->expectExceptionMessage('The cookie expiration time "string" is not valid.');
-        $cookie = new Cookie('foo', 'bar', 'string');
+        new Cookie('foo', 'bar', 'string');
     }
 }