[BUGFIX] Fix locales related warning

class.tinymce.php

@@ -82,7 +82,12 @@ class tinyMCE {
 		}
 
 		// language conversion from TLD to iso631
-		if (class_exists('t3lib_l10n_Locales')) {
+		if (class_exists('\TYPO3\CMS\Core\Localization\Locales')) {
+			/** @var $locales \TYPO3\CMS\Core\Localization\Locales */
+			$locales = t3lib_div::makeInstance('\TYPO3\CMS\Core\Localization\Locales');
+			$locales->initialize();
+			$isoArray = $locales->getIsoMapping();
+		} elseif (class_exists('t3lib_l10n_Locales')) {
 			/** @var $locales t3lib_l10n_Locales */
 			$locales = t3lib_div::makeInstance('t3lib_l10n_Locales');
 			$isoArray = $locales->getIsoMapping();