atm, because ;:-_=+ have diff keycodes based on the platform (Firefox-vs-everyone-else), we don't expose identifiers for these keys for keybindings.  we should add a pseudo one and bind to the right value on the fly.

specifically, we should be able to do:
{ "Alt-Minus": "PASS" }

and have that resolve to Alt-173 or Alt-189 automatically.