◆ Chrome ~59 : DOMException
◆ Firefox54
  ◆ sessionStorage : Exception (Component is not available)
  ◆ localStorage : SecurityError

SessionStorage や LocalStorage は使えないみたい

使おうとすると
Uncaught DOMException: Failed to read the 'sessionStorage' property from 'Window': Access is denied for this document.

みたいな例外

about:blank で JavaScript の実行試してるときには注意ですね