Remove unnecessary defined('ENVIRONMENT') checks

As suggested in issue #2134 & PR #2149
diff --git a/system/helpers/smiley_helper.php b/system/helpers/smiley_helper.php
index 186b24c..c2f50ec 100644
--- a/system/helpers/smiley_helper.php
+++ b/system/helpers/smiley_helper.php
@@ -213,7 +213,7 @@
 	 */
 	function _get_smiley_array()
 	{
-		if (defined('ENVIRONMENT') && file_exists(APPPATH.'config/'.ENVIRONMENT.'/smileys.php'))
+		if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/smileys.php'))
 		{
 			include(APPPATH.'config/'.ENVIRONMENT.'/smileys.php');
 		}