Widgets: Default to "custom URL" in the image widget.

This changes the default value for `link_type` in the image widget
schema to 'custom'.

Props bor0, desrosj.
Fixes #41629.

Built from https://develop.svn.wordpress.org/trunk@41696


git-svn-id: http://core.svn.wordpress.org/trunk@41530 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41695';
+$wp_version = '4.9-alpha-41696';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-includes/widgets/class-wp-widget-media-image.php

@@ -92,7 +92,7 @@ class WP_Widget_Media_Image extends WP_Widget_Media {
 				'link_type' => array(
 					'type' => 'string',
 					'enum' => array( 'none', 'file', 'post', 'custom' ),
-					'default' => 'none',
+					'default' => 'custom',
 					'media_prop' => 'link',
 					'description' => __( 'Link To' ),
 					'should_preview_update' => true,