Support dynamic import in vanilla template for Babel v7

[pshrmn]

What kind of change does this PR introduce?

This PR enables use of dynamic import() in the vanilla template.

Fixes #1930

What is the current behavior?

A syntax error occurs.

What is the new behavior?

import() works as expected.

Checklist:

• Documentation
• Tests
• Ready to be merged
• Added myself to contributors table

I split the way that the change is added based on how Parcel does it internally.

v7 should be ready, it simply uses parserOpts.

v6 could use some work. My "fix" uses a plugin, which is what Parcel does for Babel v6. Parcel creates a custom plugin that is essentially the same as babel-plugin-syntax-dynamic-import. That wasn't playing nicely when I tried to do the same, so I updated the babel.6.26.js module to support babel-plugin-syntax-dynamic-import. I don't like this solution, particularly because the babel.6.26.min.js module wasn't updated, but it wasn't immediately obvious where these static files get generated.

Edit: I realized why the custom plugin wasn't working. getDefaultCode serializes the return object, so the function is transformed into null. I think the best solution will be to use babel-plugin-syntax-dynamic-import provided I figure out how to generate the minified Babel 6 module.

[lbogdan]

@pshrmn Very nice!

Doesn't seem to be working with v6, though? http://pr1931.cs.lbogdan.tk/s/muddy-field-v05k2

[pshrmn]

@lbogdan I think that is because it is using the minified version, which I didn't fix.

[pshrmn]

Ideally I would prefer to get Babel 6 working without touching those static files, but if that is the best approach, I would rather not try manually editing the minified version. Are those modules generated by some external script?

[pshrmn]

I removed the Babel 6 support for now. Both static Babel files were added in #446, so I think that the builds must have happened externally.

[CompuIves]

Ahh, good point! I think we can merge this one in the meantime. I think I got the other ones by building babel-standalone with webpack.

[pshrmn]

Does the PR build through cs.lbogdan.tk no longer work? I wanted to do a sanity check that this still works before pinging about getting it merged but I'm getting a 503 error.

[lbogdan]

Hey @pshrmn ,

We recently made some improvements to the PR building workflow, while moving it to a different domain, please push a new (empty) commit so that it will pick up and build this PR.

[lbogdan]

Or you can merge master, as there were a few changes in the meanwhile. 🙂

[pshrmn]

I think that this is fine to merge. I'm not sure why the integration test is failing; the failing sandbox (https://codesandbox.io/s/6w66jzw3mn) is a Preact starter while this PR only affects Parcel templates.