Bug#906876: xul-ext-scrapbook no longer works with firefox-esr 60

[Moritz Mühlenhoff]

On Tue, Aug 21, 2018 at 09:51:34PM +0300, Adrian Bunk wrote:
> Package: xul-ext-scrapbook
> Version: 1.5.13-3
> Severity: serious
> 
> XUL addons are no longer supported. 

Seems dead upstream, no release in over two years, let's remove?

Cheers,
        Moritz