#4 add-on breaks nightly json view

Hi, this addon breaks the nightly feature for json rendering: instead of displaying the enhanced page, I see plain text only. Test URL: http://jsonplaceholder.typicode.com/posts/1 Rendering in nightly with add-on enabled: https://dl.dropboxusercontent.com/u/24468/jsonrendering.png Rendering in nightly with add-on disabled: https://dl.dropboxusercontent.com/u/24468/jsonrenderingok.png