Style Engine: Try simple approach for consolidating styles into a sin…

…gle style tag

lib/block-supports/layout.php

@@ -166,7 +166,7 @@ function gutenberg_render_layout_support_flag( $block_content, $block ) {
 		1
 	);
 
-	gutenberg_enqueue_block_support_styles( $style );
+	WP_Style_Engine_Gutenberg::get_instance()->add_style( $class_name, $style );
 
 	return $content;
 }

lib/class-wp-style-engine.php

@@ -0,0 +1,69 @@
+<?php
+/**
+ * WP_Style_Engine class
+ *
+ * @package Gutenberg
+
+ */
+
+/**
+ * Singleton class representing the style engine.
+ *
+ * Consolidates rendering block styles to reduce duplication and streamline
+ * CSS styles generation.
+ *
+ * @since 6.0.0
+ */
+class WP_Style_Engine_Gutenberg {
+	/**
+	 * Registered CSS styles.
+	 *
+	 * @since 5.5.0
+	 * @var array
+	 */
+	private $registered_styles = array();
+
+	/**
+	 * Container for the main instance of the class.
+	 *
+	 * @since 5.5.0
+	 * @var WP_Style_Engine_Gutenberg|null
+	 */
+	private static $instance = null;
+
+	public function __construct() {
+		// Borrows the logic from `gutenberg_enqueue_block_support_styles`.
+		$action_hook_name = 'wp_footer';
+		if ( wp_is_block_theme() ) {
+			$action_hook_name = 'wp_enqueue_scripts';
+		}
+		add_action(
+			$action_hook_name,
+			array( $this, 'output_styles' )
+		);
+	}
+
+	/**
+	 * Utility method to retrieve the main instance of the class.
+	 *
+	 * The instance will be created if it does not exist yet.
+	 *
+	 * @return WP_Style_Engine_Gutenberg The main instance.
+	 */
+	public static function get_instance() {
+		if ( null === self::$instance ) {
+			self::$instance = new self();
+		}
+
+		return self::$instance;
+	}
+
+	public function add_style( $key, $value ) {
+		$this->registered_styles[ $key ] = $value;
+	}
+
+	public function output_styles() {
+		$style = implode( "\n", $this->registered_styles );
+		echo "<style>$style</style>\n";
+	}
+}

lib/load.php

@@ -112,6 +112,11 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/global-styles.php';
 require __DIR__ . '/pwa.php';
 
+// TODO: Before this PR merges, move this to be a part of the style engine package.
+// Part of the build process should be to copy the PHP file to the correct location,
+// similar to the loading behaviour in `blocks.php`.
+require __DIR__ . '/class-wp-style-engine.php';
+
 require __DIR__ . '/block-supports/elements.php';
 require __DIR__ . '/block-supports/colors.php';
 require __DIR__ . '/block-supports/typography.php';