Editor: In `_WP_Editors::wp_link_query`, allow filtering empty results.

Previously, it was not possible to hook into the `wp_link_query` filter to add custom entries when the 
query returned no posts.

Props mitraval192, msebel.
Fixes #41825.

Built from https://develop.svn.wordpress.org/trunk@41346


git-svn-id: http://core.svn.wordpress.org/trunk@41179 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-editor.php

@@ -1623,9 +1623,6 @@ final class _WP_Editors {
 		// Do main query.
 		$get_posts = new WP_Query;
 		$posts = $get_posts->query( $query );
-		// Check if any posts were found.
-		if ( ! $get_posts->post_count )
-			return false;
 
 		// Build results.
 		$results = array();
@@ -1665,7 +1662,9 @@ final class _WP_Editors {
 		 * }
 		 * @param array $query  An array of WP_Query arguments.
 		 */
-		return apply_filters( 'wp_link_query', $results, $query );
+		$results = apply_filters( 'wp_link_query', $results, $query );
+
+		return ! empty( $results ) ? $results : false;
 	}
 
 	/**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41345';
+$wp_version = '4.9-alpha-41346';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.