feat(sourceMap): Make source-mapping of multi-files component working…

[csailly]

PR for issue #36 Code coverage doesn't work on files linked with "src="

[eddyerburgh]

This is awesome, thanks so much 🙂

[Toilal]

It still doesn't work with lang="ts" (TypeScript)

[dinvlad]

Hmm, it works if I set

<script lang="ts">
  export { default } from './component';
</script>

but not if I use

<script src="./component.ts"></script>

Could this be improved to include the second use case?

[eddyerburgh]

@dinvlad could you please open an issue. Then I can keep track of the bug and look into fixing it