test: add test for debugging one line files

This commit adds a regression test for debugging of
single line files.

Refs: https://github.com/nodejs/node/issues/4297
PR-URL: https://github.com/nodejs/node/pull/4298


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>