Fix memory leak in getDirectoriesFoundInManifest() (#11205)

* Fixes #11197

The 'while' loop was causing a memory leak, replaced with an 'if' to match the correct functionality.

* Removed blank lines.

* Add back while loop and added an extra condition to prevent infinite loop.

core/FileIntegrity.php

@@ -255,13 +255,12 @@ class FileIntegrity
             $directory = $file;
 
             // add this directory and each parent directory
-            while( ($directory = dirname($directory)) && $directory != '.' ) {
+            while( ($directory = dirname($directory)) && $directory != '.' && $directory != '/') {
                 $directories[] = $directory;
             }
         }
         $directories = array_unique($directories);
         return $directories;
-
     }
 
     protected static function getPluginsFoundInManifest()
@@ -465,4 +464,4 @@ class FileIntegrity
         return null;
     }
 
-}
+}
\ No newline at end of file