Oh, were we talking or even considering non opensource programs? It absolutely couldn't cross my mind that was the case.
Discussion
If you are using M$-Winbugs or any other close source toy, you have much bigger problems than trusting a browser extension with your nsec.
I just want to add "reproducible/verifiable builds" to the open source solution to reply to the "the problem with verifying open source code" comment.
Please take it easy, simply understand what I wrote and don't make assumptions on what I use, is... useles :)