TinyMCE:

- Go back to encoding the editor content only when TinyMCE is used.
- Add check and encode `</textarea>` if present.
See #32425.

git-svn-id: https://develop.svn.wordpress.org/trunk@33187 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-editor.php

@@ -251,6 +251,11 @@ final class _WP_Editors {
 			'<textarea' . $editor_class . $height . $tabindex . $autocomplete . ' cols="40" name="' . esc_attr( $set['textarea_name'] ) . '" ' .
 			'id="' . $editor_id_attr . '">%s</textarea></div>' );
 
+		// Prepare the content for the Visual or Text editor
+		if ( self::$this_tinymce ) {
+			add_filter( 'the_editor_content', 'format_for_editor', 10, 2 );
+		}
+
 		/**
 		 * Filter the default editor content.
 		 *
@@ -270,6 +275,10 @@ final class _WP_Editors {
 			$content = apply_filters( 'richedit_pre', $content );
 		}
 
+		if ( false !== stripos( $content, 'textarea' ) ) {
+			$content = preg_replace( '%</textarea%i', '&lt;/textarea', $content );
+		}
+
 		printf( $the_editor, $content );
 		echo "\n</div>\n\n";