facebook.com and related properties are currently unsupported

Currently, all Facebook properties are unsupported. These include:
- facebook.com
- messenger.com

Here's what we know so far. Facebook uses `contenteditable` fields for all user input. I believe these `contenteditable` fields are backed by React and use the virtual DOM. This means that the normal way we handle `contenteditable` fields (with the browser's built in Range functionality) do not work. We've tried:
- replacing `innerHTML` for the whole `contenteditable` field
- this doesn't work at all — the field becomes completely inaccessible