Ensure that the autosave happens on empty posts in the native apps. (#…

…23233)

On the native apps, the publish button is managed by native code on
the apps (non Gutenberg/JS code). In order to update the status of the
publish button correctly we need to autosave even when there is no
content, in order to send that information across the native code.

packages/editor/src/store/selectors.js

@@ -16,6 +16,7 @@ import { isInTheFuture, getDate } from '@wordpress/date';
 import { addQueryArgs } from '@wordpress/url';
 import { createRegistrySelector } from '@wordpress/data';
 import deprecated from '@wordpress/deprecated';
+import { Platform } from '@wordpress/element';
 
 /**
  * Internal dependencies
@@ -545,7 +546,8 @@ export function isEditedPostSaveable( state ) {
 	return (
 		!! getEditedPostAttribute( state, 'title' ) ||
 		!! getEditedPostAttribute( state, 'excerpt' ) ||
-		! isEditedPostEmpty( state )
+		! isEditedPostEmpty( state ) ||
+		Platform.OS === 'native'
 	);
 }