[Pkg-mozext-maintainers] Bug#925337: webext-ublock-origin: deactivated with Firefox 66

[Olivier]

Hello,

I just found out that the manifest.json in webext-ublock-origin contains an 
incorrect value. The value 'split' of 'incognito' is not supported in Firefox 
(https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/
manifest.json/incognito).
After removing it, the Ublock extension is back.

Regards
Olivier