I18N, Script Loader: Don't register empty locale data objects.

For `wp.i18n` the library [https://github.com/messageformat/Jed Jed] was initially used which was throwing an error if a domain was not registered but used in a translate function. Later, the library was replaced by [https://github.com/aduth/tannin Tannin] which no longer requires the domain to be registered and thus we can avoid printing an empty-ish translations script that doesn't add any translations.

Props jsnajdr.
Fixes #55250.
Built from https://develop.svn.wordpress.org/trunk@52937


git-svn-id: http://core.svn.wordpress.org/trunk@52526 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class.wp-scripts.php

@@ -599,8 +599,7 @@ class WP_Scripts extends WP_Dependencies {
 		$json_translations = load_script_textdomain( $handle, $domain, $path );
 
 		if ( ! $json_translations ) {
-			// Register empty locale data object to ensure the domain still exists.
-			$json_translations = '{ "locale_data": { "messages": { "": {} } } }';
+			return false;
 		}
 
 		$output = <<<JS

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-52936';
+$wp_version = '6.0-alpha-52937';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.