Proof of concept: Codemirror as scriptmodule dep of block editor

[sirreal]

What?

Proof of concept and demonstration of WordPress/wordpress-develop#8024 in practice.

Builds on #60155 and using WordPress/wordpress-develop#8024 to add codemirror as an on-demand imported external dependency.

DEWP does not currrently handle these dependencies, so the block editor asset file needs to be manually modified to handle the script module dependencies. After building, change build/block-editor/index.min.asset.php to look like this:

<?php return array('dependencies' => array(
	array( 'type' => 'module', 'id' => '@codemirror/commands', ),
	array( 'type' => 'module', 'id' => '@codemirror/lang-css', ),
	array( 'type' => 'module', 'id' => '@codemirror/lang-html', ),
	array( 'type' => 'module', 'id' => '@codemirror/state', ),
	array( 'type' => 'module', 'id' => '@codemirror/view', ),
	array( 'type' => 'module', 'id' => 'codemirror', ),

	'react', 'react-dom', 'wp-a11y', 'wp-api-fetch', 'wp-blob', 'wp-blocks', 'wp-commands', 'wp-components', 'wp-compose', 'wp-data', 'wp-date', 'wp-deprecated', 'wp-dom', 'wp-element', 'wp-hooks', 'wp-html-entities', 'wp-i18n', 'wp-is-shallow-equal', 'wp-keyboard-shortcuts', 'wp-keycodes', 'wp-notices', 'wp-polyfill', 'wp-preferences', 'wp-primitives', 'wp-private-apis', 'wp-rich-text', 'wp-style-engine', 'wp-token-list', 'wp-url', 'wp-warning', 'wp-wordcount'), 'version' => 'da526c264560c67bccdf');

Why?

Script modules are ideal for deferred or conditional loading of JavaScript assets.

How?

Use the implementation for scripts to depend on script modules proposed in WordPress/wordpress-develop#8024 to load codemirror on demand.

Testing Instructions

Run this along with WordPress/wordpress-develop#8024. Load the editor and add a custom HTML block. In the network tab you'll see that codemirror assets are loaded on demand when the block is added. There are some problems with the block but that's beyond the scope of this proof of concept.

Screenshots or screencast

demo.mov

[sirreal]

This is porting some module dependency changes from WordPress/wordpress-develop#8024.