Bad coverage information when loaders are used

[simlu]

Opening this so there is an actual issue tracked on this repo and to get some attention.

---

There is a problem when reporting test coverage while using loaders. I'm not going to go into too much detail here since I don't fully understand the issue and don't want to give incorrect information. However there is plenty to read up on.

Relevant tickets:

• Inconsistent coverage information when loaders used node#41387
• Incorrect branch coverage when loaders used bcoe/c8#325

---

Why is this important to fix?
Using loaders and query string parameters is the only (reasonable) way to invalidate imports in esm. This makes it almost mandatory to use in test libraries.

Would be great if you could give some feedback! Cheers, L~