Looks like Firefox also generates locations with names like
`bound (self-hosted:951:0)`. We check for `self-hosted`, but not for
`self-hosted` with stuff after it following a colon. We should ignore
these too, otherwise we can end up with stuff on our stack that we don't
expect. This was causing Firefox profiles not to load because we
completed building the profile with a non-empty stack.
Attached is a profile that errors without this patch and successfully renders
with this patch.
[copy.json.zip](https://github.com/jlfwong/speedscope/files/2350583/copy.json.zip)
b6190362b4