RichText: Fix delete key in empty contenteditables (#5348)

Author: youknowriad

lib/client-assets.php

@@ -85,7 +85,7 @@ function gutenberg_register_scripts_and_styles() {
 	wp_register_script(
 		'wp-utils',
 		gutenberg_url( 'utils/build/index.js' ),
-		array(),
+		array( 'tinymce-latest' ),
 		filemtime( gutenberg_dir_path() . 'utils/build/index.js' )
 	);
 	wp_register_script(

utils/dom.js

@@ -2,6 +2,7 @@
  * External dependencies
  */
 import { includes } from 'lodash';
+import tinymce from 'tinymce';
 
 /**
  * Browser dependencies
@@ -57,8 +58,14 @@ export function isHorizontalEdge( container, isReverse, collapseRanges = false )
 	}
 
 	const maxOffset = node.nodeType === TEXT_NODE ? node.nodeValue.length : node.childNodes.length;
+	const editor = tinymce.get( node.id );
 
-	if ( ! isReverse && offset !== maxOffset ) {
+	if (
+		! isReverse &&
+		offset !== maxOffset &&
+		// content editables with only a BR element are considered empty
+		( ! editor || ! editor.dom.isEmpty( node ) )
+	) {
 		return false;
 	}