Fix create temp folder if it does not exist

thirdparty/tinymce/tiny_mce_gzip.php

@@ -16,10 +16,14 @@ require_once $frameworkPath . '/core/Constants.php';
 
 // Handle incoming request if it's a script call
 if (TinyMCE_Compressor::getParam("js")) {
-	// Default settings
+    $tempFolder = TEMP_FOLDER . '/tinymce-cache';
+    if (!file_exists($tempFolder)) {
+        mkdir($tempFolder);
+    }
+        // Default settings
 	$tinyMCECompressor = new TinyMCE_Compressor(array(
 		// CUSTOM SilverStripe
-		'cache_dir' => TEMP_FOLDER.'/tinymce-cache'
+		'cache_dir' => $tempFolder
 		// CUSTOM END
 	));