Block Editor: Enqueue script modules via enqueue_block_assets action

[sirreal]

Trac ticket: https://core.trac.wordpress.org/ticket/64360

​The enqueue_block_assets action is used to add scripts and styles in the block editor's iframe.

It should be possible to add script modules to the block editor's iframe as well.

See:

_wp_get_iframed_editor_assets and ​its documentation.
The WP_Script_Modules class.
The block editor Iframe component in Gutenberg.
This will likely require a new method or exposing more of the script modules internal data so that a specific WP_Script_Modules instance can be used for the iframed assets. See #60597.

Requires Gutenberg changes to the block editor. See WordPress/gutenberg#73765.

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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[westonruter]

Relatedly, I just learned that PHP 8.5 has clone with support for setting properties on a cloned object: https://www.php.net/releases/8.5/en.php#clone-with

[westonruter]

Would this be better?

Suggested change

	$clone = new WP_Script_Modules();
	$clone->registered = $this->registered;
	$clone->dependents_map = $this->dependents_map;
	$clone->modules_with_missing_dependencies = $this->modules_with_missing_dependencies;
	$clone = clone $this;
	$clone->queue = array();
	$clone->done = array();

[sirreal]

The result is the same, right? I don't mind either way, if you have reasons to prefer one or the other I'd be happy to know.

[westonruter]

Mutating the queue member variable is done elsewhere in core for WP_Styles.

And this is just changing two members instead of three. And these two members feel less internal than the others, meaning we won't need to worry about ensuring other members get copied.

And if I understand correctly, resetting the queue and done are conceptually closer to what is desired: reset the state of what has been queued/printed to capture what is newly to be queued.

[westonruter]

I learned of a hack/feature in PHP to allow setting private members in PostStatus Slack. This should should have the same effect, including my suggestion below:

Suggested change

	$wp_script_modules = $wp_script_modules->clone_without_enqueued_modules();
	$wp_script_modules = clone $wp_script_modules;
	( function () {
	$this->done = array();
	$this->queue = array();
	} )->call( $wp_script_modules );

[sirreal]

That's wild. I can't believe it works and private properties are accessible in the closure.