Import flow-error-toggler userscript from @yungsters
Import flow-error-toggler userscript from @yungsters

Just dumping this in here for now with no automation, because
userscripts have to be installed manually anyway.

For other scripts, see:

  https://github.com/yungsters/phabricator-scripts/

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent