TinyMCE: fix freezing the editor when wpautop is disabled and a paragraph starts with a lot of white space characters.

Fixes #38294.
Built from https://develop.svn.wordpress.org/trunk@39204


git-svn-id: http://core.svn.wordpress.org/trunk@39144 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/tinymce/plugins/wordpress/plugin.js

@@ -131,10 +131,9 @@ tinymce.PluginManager.add( 'wordpress', function( editor ) {
 			}
 
 			// Remove spaces from empty paragraphs.
-			// Avoid backtracking, can freeze the editor. See #35890.
-			// (This is also quite faster than using only one regex.)
+			// Try to avoid a lot of backtracking, can freeze the editor. See #35890 and #38294.
 			event.content = event.content.replace( /<p>([^<>]+)<\/p>/gi, function( tag, text ) {
-				if ( /^(&nbsp;|\s|\u00a0|\ufeff)+$/i.test( text ) ) {
+				if ( text === '&nbsp;' || ! /\S/.test( text ) ) {
 					return '<p><br /></p>';
 				}
 

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta3-39203';
+$wp_version = '4.7-beta3-39204';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.