[Form] Remove unused private method

Form.php

@@ -1137,19 +1137,4 @@ private function viewToNorm($value)
 
         return $value;
     }
-
-    /**
-     * Utility function for indenting multi-line strings.
-     *
-     * @param string $string The string
-     * @param int    $level  The number of spaces to use for indentation
-     *
-     * @return string The indented string
-     */
-    private static function indent($string, $level)
-    {
-        $indentation = str_repeat(' ', $level);
-
-        return rtrim($indentation.str_replace("\n", "\n".$indentation, $string), ' ');
-    }
 }