Exclude Iterator helpers from polyfills (#69070)

* Exclude Iterator helpers from polyfills
* Use assertEqualSets
* Ignore bundled packages

Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>

packages/babel-preset-default/polyfill-exclusions.js

@@ -28,4 +28,9 @@ module.exports = [
 	//
 	// @see https://github.com/WordPress/gutenberg/pull/67230
 	/^es(next)?\.set\./,
+	// Remove Iterator feature polyfills.
+	// For the same reasoning as for Set exlusion above, we're excluding all iterator helper polyfills.
+	//
+	// @see https://github.com/WordPress/wordpress-develop/pull/8224#issuecomment-2636390007.
+	/^es(next)?\.iterator\./,
 ];

phpunit/script-dependencies-test.php

@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * @group script-dependencies
+ */
+class Test_Script_Dependencies extends WP_UnitTestCase {
+	public $bundled_scripts = array( 'wp-upload-media' );
+
+	/**
+	 * Tests for accidental `wp-polyfill` script dependents.
+	 */
+	public function test_polyfill_dependents() {
+		$scripts            = wp_scripts();
+		$registered_scripts = $scripts->registered;
+		$dependents         = array();
+
+		// Iterate over all registered scripts, finding dependents of the `wp-polyfill` script.
+		// Based on private `WP_Scripts::get_dependents` method.
+		foreach ( $registered_scripts as $registered_handle => $args ) {
+			// Ignore bundled packages, they don't load separate polyfills.
+			if ( in_array( $registered_handle, $this->bundled_scripts, true ) ) {
+				continue;
+			}
+
+			if ( in_array( 'wp-polyfill', $args->deps, true ) ) {
+				$dependents[] = $registered_handle;
+			}
+		}
+
+		// This list should get smaller over time as we remove `wp-polyfill` dependencies.
+		// If the list update is intentional, please add a comment explaining why.
+		$expected = array(
+			'react',
+			'wp-blob',
+			'wp-block-editor',
+			'wp-block-library',
+			'wp-blocks',
+			'wp-edit-site',
+			'wp-core-data',
+			'wp-editor',
+			'wp-router',
+			'wp-url',
+			'wp-widgets',
+		);
+
+		$this->assertEqualSets( $expected, $dependents );
+	}
+}