Tests for import attributes

[nicolo-ribaudo]

Repo: https://github.com/tc39/proposal-import-attributes/
Spec text: https://tc39.es/proposal-import-attributes/
ECMA-262 PR: tc39/ecma262#3057

Import assertions have recently been changed to be "import attributes", with the following changes:

1. the keyword is now with instead of assert
2. the property in the dynamic import options bag is now with
3. there are fewer restrictions about what a host can do with the given attributes

Additionally, the old syntax is still specified but marked as "normative optional, deprecated", and there is an optional fallback to lookup the assert property in the dynamic import options bag if with is undefined.

I don't think we can test (3), but for (1) and (2) we can copy the existing tests replacing assert with with. Additionally, we may need a test for dynamic import with both with and assert defined in the options bag.

Ref #3780

[JonnyTizz]

Hi! I was just browsing issues and happened across this one.

It looks like the related PR was split, and the split parts were all merged successfully. Does this mean this issue is resolved and can be closed?

Thanks!

[nicolo-ribaudo]

Yes, thanks! :)