Support import(...) in ESTree->Terser conversion

[RReverser]

A bit crude, since Terser doesn't have a dedicated dynamic import AST node type, but verified that it works.

Fixes #11303 (now for real).

[curiousdannii]

Should you make this a PR upstream?

https://github.com/terser/terser/blob/7aad3cbfbf194c5e9af56f18dd348f9abe7b407a/lib/mozilla-ast.js#L451

[RReverser]

No, our version has already diverged, plus as mentioned in the description this is a limited support just for our use-case; proper upstream support would be much more involved and different from this PR.

[RReverser]

Tests passed!

[sbc100]

Should there be a test case as part of this change?

[RReverser]

Mayyyybe 😅

[RReverser]

I guess I was somewhat discouraged by your TODO / comment here:

emscripten/tests/test_other.py

Lines 186 to 188 in a534224

	# TODO(sbc): Test that this is actually runnable. We currently don't have
	# any tests for EXPORT_ES6 but once we do this should be enabled.
	# self.assertContained('hello, world!', self.run_js('hello_world.mjs'))

But I guess I could add a test that simply verifies this combination of flags compiles at all.

[RReverser]

(working on it)

[sbc100]

Sounds good. Just added a compile-only test would be acceptable for now.. given that TODO.

If you are interested in this area perhaps we might want to find a way to do actual testing of the generated ES6 modules.

[RReverser]

Added a test and verified that it fails without the fix and works with the fix.

[sbc100]

lgtm but I don't know the terser code.. @azakai can you take a look?

[RReverser]

lgtm but I don't know the terser code

FWIW I kind of know that file because I implemented quite a few parts of it back in 2014 when it was still UglifyJS, but an extra pair of eyes is surely welcome 😅

[sbc100]

ok sgtm