Editor: Add custom fields meta box support in the block editor.

This brings support for the custom fields meta box into the new block editor.

The `webpack` and `copy-webpack-plugin` packages have also been updated.

This does not bump the `@wordpress` packages like in [43861] because of conflicts with package versions already installed in `trunk`. The packages will be brought up to date in a subsequent merge.

Merges [43861] and [43863] into trunk.

See #45145.
Fixes #45257.
Built from https://develop.svn.wordpress.org/trunk@44260


git-svn-id: http://core.svn.wordpress.org/trunk@44090 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/script-loader.php

@@ -235,6 +235,7 @@ function wp_default_packages_scripts( &$scripts ) {
 		'data'                               => array(
 			'lodash',
 			'wp-compose',
+			'wp-deprecated',
 			'wp-element',
 			'wp-is-shallow-equal',
 			'wp-polyfill',
@@ -351,6 +352,7 @@ function wp_default_packages_scripts( &$scripts ) {
 			'lodash',
 			'wp-blocks',
 			'wp-data',
+			'wp-deprecated',
 			'wp-escape-html',
 			'wp-polyfill',
 		),

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.1-alpha-44257';
+$wp_version = '5.1-alpha-44260';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.