Add tests for stack traces produced by `--enable-source-maps`

[coreyfarrell]

Newer versions of node.js have built-in support for processing source-maps. We should test against some stack traces produced by --enable-source-maps.

Edit: I've been experimenting with --enable-source-maps and everything seems to work correctly though I think I'm likely only hitting nominal conditions.

[conartist6]

Any update on whether there's action needed on this? It sounds like you're saying that the stack trace format is unchanged with sourcemaps just providing different file names and line numbers, which is what I would expect. If there is further action needed, I'd really appreciate it if you would open an issue against stack-tools!