Add more JavaScript tests

[Luni-4]

It would be helpful to add tests for JavaScript grammar starting from this file (v0.19 #552):

• one.zip

[Luni-4]

We can use insta tests now

[marco-c]

We can formulate them as insta tests, but we still have to add them.

[Luni-4]

@marco-c

We have insta tests (pdf.js) for this grammar, it is a big dataset, we can close this issue