WebExtensions: "clipboardRead" and "clipboardWrite"

I have a “legacy” addon that I am looking to port to the new WebExtension format. It copies to and from the clipboard however, WebEx as of yet does not support the clipboard (Bug 1197451). Is there a general idea as to when this feature is to be added?

It’s not a blocker for the mid-year launch, so it’s unlikely to make it then, unless someone wants to take the initiative to implement it.

Thank you for the information.