toolkit/content/debug.js
debug.js is now included by globalOverlay.js, but if that's not in your
scope you can just #include debug.js directly.
NS_ASSERT() shows a dialog box containing a stack trace when it's called
with a condition that isn't true. The dialog box will be suppressed in
final builds, but in nightlies and alphas, it's useful for encouraging
bug submissions. To disable the dialogs, set XUL_ASSERT_PROMPT=0 in
your environment.
bug=327349
r=darin@meer.net, gavin.sharp@gmail.com
joe%retrovirus.com