Fixes issue with wysiwyg editor re-creating thumbnails (OpenMage#261)

* Fixes issue with wysiwyg editor re-creating thumbnails each load causing performance / database connection limit issues.

Author: trabulium

app/code/core/Mage/Cms/Model/Wysiwyg/Images/Storage.php

@@ -339,13 +339,13 @@ public function getThumbnailPath($filePath, $checkFile = false)
      */
     public function getThumbnailUrl($filePath, $checkFile = false)
     {
-        $mediaRootDir = $this->getHelper()->getStorageRoot();
+        $mediaRootDir = Mage::getConfig()->getOptions()->getMediaDir() . DS;
 
         if (strpos($filePath, $mediaRootDir) === 0) {
             $thumbSuffix = self::THUMBS_DIRECTORY_NAME . DS . Mage_Cms_Model_Wysiwyg_Config::IMAGE_DIRECTORY
                 . DS . substr($filePath, strlen($mediaRootDir));
 
-            if (! $checkFile || is_readable($mediaRootDir . $thumbSuffix)) {
+            if (! $checkFile || is_readable($this->getHelper()->getStorageRoot() . $thumbSuffix)) {
                 $randomIndex = '?rand=' . time();
                 $thumbUrl = $this->getHelper()->getBaseUrl() . Mage_Cms_Model_Wysiwyg_Config::IMAGE_DIRECTORY
                     . DS . $thumbSuffix;