Replace null in ArrayExpression and ArrayPattern with Null node

[fisker]

Description

Add a dummy node for null in array, so we can attach comments. This solution should work for other similar problem, like #9787 (comment) or for(;;);

Fixes #1013
Fixes #9299

Checklist

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory).
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨

[sosukesuzuki]

Please add a comment that explain motivation to introduce Null node or link to this PR.

[fisker]

Done.

[sosukesuzuki]

@thorn0 Could you review?

[brodybits]

This solution should work for other similar problem, like #9787 (comment) or for(;;);

Are these tracked somewhere?

By for(;;) do you mean something like for(/*a*/;;)?

And I thought of one more case:

call(foo,,/*a*/,/*b*/,bar)

[fisker]

By for(;;) do you mean something like for(/a/;;)?

Yes, opened an issue to track this #10046

[so1ve]

🤔 Still blocked?