So here is the full stacktrace after I set the constant:
/Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-firefox/
jssh_socket.rb:643:in `val_or_object': undefined expression
JsshTemp["o3kgf2"].webProgress (JsshUndefinedValueError)
from /Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-
firefox/jssh_socket.rb:666:in `invoke'
from /Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-
firefox/jssh_socket.rb:881:in `method_missing'
from /Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-
firefox/modal_dialog.rb:138:in `wait'
from /Library/Ruby/Gems/1.8/gems/vapir-common-1.7.1/lib/vapir-common/
waiter.rb:127:in `try_for'
from /Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-
firefox/modal_dialog.rb:137:in `wait'
from /Library/Ruby/Gems/1.8/gems/vapir-firefox-1.7.1/lib/vapir-
firefox/element.rb:211:in `wait'
from /Library/Ruby/Gems/1.8/gems/vapir-common-1.7.1/lib/vapir-common/
element.rb:88:in `submit'
from ff-vapir.rb:18
I'm running Firefox version 3.6.12. Let me know if you need any more
info!