Index: src/wp-includes/script-loader.php
===================================================================
--- src/wp-includes/script-loader.php	(revision 48709)
+++ src/wp-includes/script-loader.php	(working copy)
@@ -723,6 +723,11 @@
 	$scripts->add( 'jquery-core', '/wp-includes/js/jquery/jquery.js', array(), '1.12.4-wp' );
 	$scripts->add( 'jquery-migrate', "/wp-includes/js/jquery/jquery-migrate$suffix.js", array(), '1.4.1' );
 
+	// Backwards compatibility: Makes it easy for plugins and themes to enqueue jQuery with jQuery Migrate in WordPress 5.5.
+	// Note: This script handle will most likely be removed in WordPress 5.6 or when jQuery is updated to the latest version.
+	// Then plugins and themes that are still relaying on it will stop functioning.
+	$scripts->add( 'jquery-migrate-compat-5.5', false, array( 'jquery-core', 'jquery-migrate' ), '1.12.4-wp' );
+
 	// Full jQuery UI.
 	$scripts->add( 'jquery-ui-core', "/wp-includes/js/jquery/ui/core$dev_suffix.js", array( 'jquery' ), '1.11.4', 1 );
 	$scripts->add( 'jquery-effects-core', "/wp-includes/js/jquery/ui/effect$dev_suffix.js", array( 'jquery' ), '1.11.4', 1 );