Remove unnecessary defined('ENVIRONMENT') checks

As suggested in issue #2134 & PR #2149
diff --git a/system/helpers/text_helper.php b/system/helpers/text_helper.php
index 1c7eeaf..c255c15 100644
--- a/system/helpers/text_helper.php
+++ b/system/helpers/text_helper.php
@@ -367,7 +367,7 @@
 
 		if ( ! isset($foreign_characters) OR ! is_array($foreign_characters))
 		{
-			if (defined('ENVIRONMENT') && is_file(APPPATH.'config/'.ENVIRONMENT.'/foreign_chars.php'))
+			if (is_file(APPPATH.'config/'.ENVIRONMENT.'/foreign_chars.php'))
 			{
 				include(APPPATH.'config/'.ENVIRONMENT.'/foreign_chars.php');
 			}