Suppose there's a JS error involved, where the debugger needs to be loaded before any of the test files or JS modules. (Sometimes Venkman has trouble stepping through code that loads before it does.) It'd be really nice to have a command-line argument for runtests.py, which says "Launch the JS debugger I specify first, then load the Mochitest." If anyone besides me wants this and is willing to review, I can write up a patch.

I don't always forward-dupe, but when I do, it's to a bug that seems to already have someone who might want to review stuff! :-)