feat(static-module-record): add support for import.meta

[naugtur]

Implemented import.meta according to #291

The actual implementation of exposing import.meta.url to modules loaded by compartment-mapper is going to be a separate PR.

[kriskowal]

Let’s talk requirements for this feature at Endo Sync tomorrow. The Compartment abstraction will be aware of meta but not meta.url. For that, we need to give the hooks system a way to populate meta. The current notion is that the import/loadHook will be able to return an object with a meta property and the compartment will copy the properties to the meta object. Because some of those properties are expensive, we would have an importMetaHook that takes a meta object and add things like resolve but would only be called if a module utters import.meta in its source text.

[kriskowal]

See #291

[naugtur]

Made some progress on the implementation. Looks like it's it.

[kriskowal]

Yeah, this is on-track. The comments I’ve left pertain to the leading half of this feature, which needs to allow for usage like:

const c = new Compartment({}, {}, {
  importHook(specifier) {
    const requestUrl = locate(specifier);
    const response = await fetch(requestUrl);
    const responseText = await response.text();
    return {
      record: new StaticModuleRecord(responseText),
      meta: {url: responseURL};
    };
  },
  importMetaHook(meta) {
    meta.resolve = url => importMetaResolve(url, meta.url);
  },
});

[kriskowal]

Nice tests!

[naugtur]

@kriskowal Unless I need to put more contrnt into packages/ses/README.md I think this is ready for final review.

[kriskowal]

This is ready to land, though the specification it’s based on needs a little more time to bake. Until then, I’ve left some notes for your consideration.

[kriskowal]

…and I’m leaving a stamp so you don’t have to wait for my blessing when everything’s ready.