Added checks for objects in DB driver instead of just resources to accommodate MySQLi, and fixed check in mysqli_result.php checking for a resource.

http://codeigniter.com/bug_tracker/bug/3461/
diff --git a/system/database/drivers/mysqli/mysqli_result.php b/system/database/drivers/mysqli/mysqli_result.php
index 586c292..692d4f7 100644
--- a/system/database/drivers/mysqli/mysqli_result.php
+++ b/system/database/drivers/mysqli/mysqli_result.php
@@ -114,7 +114,7 @@
 	 */		

 	function free_result()

 	{

-		if (is_resource($this->result_id))

+		if (is_object($this->result_id))

 		{

 			mysqli_free_result($this->result_id);

 			$this->result_id = FALSE;