Move a11y HTML printing code to 6.7 compat directory (#65620)

- Ensure that the HTML printing for the @wordpress/a11y script module does not conflict with Core.
- Move the @wordpress/a11y script module code to the 6.7 compat directory.

The a11y script module HTML printing filters are set conditionally. If Core would set them, Gutenberg does not.
This ensures that duplicate HTML elements (with identical element IDs) are not added to the page.

This is necessary for compatibility with WordPress 6.7 that adds the @wordpress/a11y Script Module.

See https://core.trac.wordpress.org/changeset/59089.

---

Co-authored-by: sirreal <jonsurrell@git.wordpress.org>
Co-authored-by: michalczaplinski <czapla@git.wordpress.org>

lib/compat/wordpress-6.7/script-modules.php

@@ -102,3 +102,46 @@ function () {
 	},
 	20
 );
+
+/**
+ * Prints HTML for the a11y Script Module.
+ *
+ * a11y relies on some DOM elements to use as ARIA live regions.
+ * Ideally, these elements are part of the initial HTML of the page
+ * so that accessibility tools can find them and observe updates.
+ */
+function gutenberg_a11y_script_module_html() {
+	$a11y_module_available = false;
+
+	$get_marked_for_enqueue = new ReflectionMethod( 'WP_Script_Modules', 'get_marked_for_enqueue' );
+	$get_marked_for_enqueue->setAccessible( true );
+	$get_import_map = new ReflectionMethod( 'WP_Script_Modules', 'get_import_map' );
+	$get_import_map->setAccessible( true );
+
+	foreach ( array_keys( $get_marked_for_enqueue->invoke( wp_script_modules() ) ) as $id ) {
+		if ( '@wordpress/a11y' === $id ) {
+			$a11y_module_available = true;
+			break;
+		}
+	}
+	if ( ! $a11y_module_available ) {
+		foreach ( array_keys( $get_import_map->invoke( wp_script_modules() )['imports'] ) as $id ) {
+			if ( '@wordpress/a11y' === $id ) {
+				$a11y_module_available = true;
+				break;
+			}
+		}
+	}
+	if ( ! $a11y_module_available ) {
+		return;
+	}
+	echo '<div style="position:absolute;margin:-1px;padding:0;height:1px;width:1px;overflow:hidden;clip-path:inset(50%);border:0;word-wrap:normal !important;">'
+		. '<p id="a11y-speak-intro-text" class="a11y-speak-intro-text" hidden>' . esc_html__( 'Notifications', 'default' ) . '</p>'
+		. '<div id="a11y-speak-assertive" class="a11y-speak-region" aria-live="assertive" aria-relevant="additions text" aria-atomic="true"></div>'
+		. '<div id="a11y-speak-polite" class="a11y-speak-region" aria-live="polite" aria-relevant="additions text" aria-atomic="true"></div>'
+		. '</div>';
+}
+if ( ! method_exists( 'WP_Script_Modules', 'print_a11y_script_module_html' ) ) {
+	add_action( 'wp_footer', 'gutenberg_a11y_script_module_html' );
+	add_action( 'admin_footer', 'gutenberg_a11y_script_module_html' );
+}

lib/experimental/script-modules.php

@@ -200,44 +200,3 @@ function gutenberg_dequeue_module( $module_identifier ) {
 	_deprecated_function( __FUNCTION__, 'Gutenberg 17.6.0', 'wp_dequeue_script_module' );
 	wp_script_modules()->dequeue( $module_identifier );
 }
-
-/**
- * Prints HTML for the a11y Script Module.
- *
- * a11y relies on some DOM elements to use as ARIA live regions.
- * Ideally, these elements are part of the initial HTML of the page
- * so that accessibility tools can find them and observe updates.
- */
-function gutenberg_a11y_script_module_html() {
-	$a11y_module_available = false;
-
-	$get_marked_for_enqueue = new ReflectionMethod( 'WP_Script_Modules', 'get_marked_for_enqueue' );
-	$get_marked_for_enqueue->setAccessible( true );
-	$get_import_map = new ReflectionMethod( 'WP_Script_Modules', 'get_import_map' );
-	$get_import_map->setAccessible( true );
-
-	foreach ( array_keys( $get_marked_for_enqueue->invoke( wp_script_modules() ) ) as $id ) {
-		if ( '@wordpress/a11y' === $id ) {
-			$a11y_module_available = true;
-			break;
-		}
-	}
-	if ( ! $a11y_module_available ) {
-		foreach ( array_keys( $get_import_map->invoke( wp_script_modules() )['imports'] ) as $id ) {
-			if ( '@wordpress/a11y' === $id ) {
-				$a11y_module_available = true;
-				break;
-			}
-		}
-	}
-	if ( ! $a11y_module_available ) {
-		return;
-	}
-	echo '<div style="position:absolute;margin:-1px;padding:0;height:1px;width:1px;overflow:hidden;clip-path:inset(50%);border:0;word-wrap:normal !important;">'
-		. '<p id="a11y-speak-intro-text" class="a11y-speak-intro-text" hidden>' . esc_html__( 'Notifications', 'default' ) . '</p>'
-		. '<div id="a11y-speak-assertive" class="a11y-speak-region" aria-live="assertive" aria-relevant="additions text" aria-atomic="true"></div>'
-		. '<div id="a11y-speak-polite" class="a11y-speak-region" aria-live="polite" aria-relevant="additions text" aria-atomic="true"></div>'
-		. '</div>';
-}
-add_action( 'wp_footer', 'gutenberg_a11y_script_module_html' );
-add_action( 'admin_footer', 'gutenberg_a11y_script_module_html' );