Media: Decode HTML entities in `author_name` before sending to JS.

In `wp_prepare_attachment_for_js()`:
- Normalize behavior when author does not exist by returning '(no author)' for `authorName` in these cases.
- Decode HTML entities in `author_name`.
- Add tests for both of the above.

Props arshidkv12, ocean90, sloisel, mikeschroder.
Fixes #39955.
Built from https://develop.svn.wordpress.org/trunk@40809


git-svn-id: http://core.svn.wordpress.org/trunk@40667 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/media.php

@@ -3098,7 +3098,11 @@ function wp_prepare_attachment_for_js( $attachment ) {
 	);
 
 	$author = new WP_User( $attachment->post_author );
-	$response['authorName'] = $author->display_name;
+	if ( $author->exists() ) {
+		$response['authorName'] = html_entity_decode( $author->display_name, ENT_QUOTES, get_bloginfo( 'charset' ) );
+	} else {
+		$response['authorName'] = __( '(no author)' );
+	}
 
 	if ( $attachment->post_parent ) {
 		$post_parent = get_post( $attachment->post_parent );

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-beta1-40808';
+$wp_version = '4.8-beta1-40809';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.