Improve log lines file naming on server.

We avoid using Error.prepareStackTrace (which the node source map support also
uses) and do some hacky regexp parsing instead. This way, on the server, we get
the filename/line numbers after source map processing.

On the client we continue to get the compiled version... I guess because source
maps are implemented in the developer tools, not directly into the Error object.

(Probably should have gotten parseStack from tools/buildmessage.js instead.)

unbreaks _getCallerDetails tests.