Remove unnecessary defined('ENVIRONMENT') checks

As suggested in issue #2134 & PR #2149
diff --git a/system/helpers/html_helper.php b/system/helpers/html_helper.php
index 2d47416..7a71eb8 100644
--- a/system/helpers/html_helper.php
+++ b/system/helpers/html_helper.php
@@ -242,7 +242,7 @@
 
 		if ( ! is_array($_doctypes))
 		{
-			if (defined('ENVIRONMENT') && is_file(APPPATH.'config/'.ENVIRONMENT.'/doctypes.php'))
+			if (is_file(APPPATH.'config/'.ENVIRONMENT.'/doctypes.php'))
 			{
 				include(APPPATH.'config/'.ENVIRONMENT.'/doctypes.php');
 			}
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');
 		}
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');
 			}