Changes

* Firefox: '''Under flag''': need enable [https://developer.mozilla.org/en-US/docs/Web/Web_Components#Enabling_Web_Components_in_Firefox need enable dom.webcomponents.enabled ] in about:config]

* FirefoxOS: '''Under flagpermission needed''': use WebIDE to open `preference table` to enable dom.add '''"moz-extremely-unstable-and-will-change-webcomponents": {}''' permission in manifest.enabled on devicewebapp's '''permissions''' section