Index: wp-includes/l10n.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-includes/l10n.php	(revision 43779)
+++ wp-includes/l10n.php	(date 1543495536833)
@@ -891,6 +891,12 @@
 	$path   = untrailingslashit( $path );
 	$locale = is_admin() ? get_locale() : get_user_locale();
 
+	$json_translations = apply_filters( 'pre_load_script_textdomain', false, $handle, $domain, $path, $locale );
+
+	if ( $json_translations ) {
+		return $json_translations;
+	}
+
 	// If a path was given and the handle file exists simply return it.
 	$file_base       = $domain === 'default' ? $locale : $domain . '-' . $locale;
 	$handle_filename = $file_base . '-' . $handle . '.json';