Work perfectly just like old ieview.
I have just a bug in context menu. Normally it should show "Open by IE" but it's empty, I think the error comes from the messages.json :

Is not "contextMenu_page_label" but "contextMenu.page.label"
Is not "contextMenu_link_label" but "contextMenu.link.label"

thanks for porting this addon to WebExt.

You sould consider to port it to Chrome too.