Code Modernization: Fix dynamic properties in WP_Admin_Bar.

To fix the dynamic properties, the following changes are included:
* Removes `WP_Admin_Bar::__get()`.
* Declares `menu` as a property on the class, deprecates it, and initializes it to an empty array.
* Removes the unused 'proto' dynamic property.

Dynamic (non-explicitly declared) properties are deprecated as of PHP 8.2 and are expected to become a fatal error in PHP 9.0.

== Why remove the `WP_Admin_Bar::__get()` magic method?

tl;dr
The magic method is no longer needed.

The magic method only handled the `menu` and `proto` dynamic properties. Introducing a full set of magic methods is overkill for this class. Instead of having to maintain magic methods, this changeset instead directly addresses the 2 properties (see below).

== Why declare the `menu` property on the class?

tl;dr
To simplify the code while maintaining backwards compatibility for extenders who are using this deprecated property.

The `menu` property was introduced during the 3.1.0 ''development cycle'' as a declared property [15671]. Its purpose was to ''internally'' hold the menu structure.

During the WP 3.3.0 development cycle, it was replaced by a new `private` property called `nodes` (see [19120]).

But breakage reports from extenders caused it to be restored. [19501] added the `__get()` magic method, i.e. for handling it as a dynamic property, and deprecated it.

>We're not going to maintain compat for $menu. Suggest we make it array() and plugins will have to deal. We can throw a _deprecated_argument() and push them to use the new methods.
~ Source: [https://core.trac.wordpress.org/ticket/19371#comment:17 see #19371 comment 17]

[https://wpdirectory.net/search/01GSTW1X69TBN8FH3SY7V8KPY5 A search of the wp.org plugins and themes repository] shows that a few plugins are still using this deprecated property. To maintain backwards compatibility, `menu` is moved back to the class as a declared property, set to an empty array (as it's been since 3.3.0), and deprecated in the property's description.

== Why remove the `proto` dynamic property?

tl;dr
* It was not intended to be released in 3.1.
* There are no usages of it in Core or in the WP.org's plugin or theme directories.
* It should be safe to remove.

This property was first introduced in the WP 3.1.0 ''development cycle'' to replace the `PROTO` constant (see [16038]) for protocol handling for the admin bar's hyperlinks. [16077] replaced the property's usages with URL functions such as `get_admin_url()` and `admin_url()`. But it missed removing the property, which was no longer needed or used.

It was relocated to the `__get()` magic method as a dynamic property when the `menu` property was restored (see [19501]).

A search of WP.org's plugins and themes repositories shows no usages of the property. Core hasn't used it since the removed in [16038] before 3.1 final release. It should be safe to remove it, but committing very early in the 6.3 alpha cycle to give time for reports of usages, if there are any.

References:
* A [https://www.youtube.com/watch?v=vDZWepDQQVE&t=9362s live open public working session] where these changes were discussed and agreed to.
* [https://wiki.php.net/rfc/deprecate_dynamic_properties PHP RFC: Deprecate dynamic properties].

Follow-up to [19501], [19120], [16308], [16038], [15671].

Props antonvlasenko, hellofromTonya, jrf, markjaquith, desrosj, ironprogrammer, peterwilsoncc, SergeyBiryukov.
See #56876, #56034.
Built from https://develop.svn.wordpress.org/trunk@55580


git-svn-id: http://core.svn.wordpress.org/trunk@55092 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-admin-bar.php

@@ -19,21 +19,14 @@ class WP_Admin_Bar {
 	public $user;
 
 	/**
-	 * @since 3.3.0
+	 * Deprecated menu property.
 	 *
-	 * @param string $name
+	 * @since 3.1.0
-	 * @return string|array|void
+	 * @deprecated 3.3.0 Modify admin bar nodes with WP_Admin_Bar::get_node(),
+	 *                   WP_Admin_Bar::add_node(), and WP_Admin_Bar::remove_node().
+	 * @var array
 	 */
-	public function __get( $name ) {
+	public $menu = array();
-		switch ( $name ) {
-			case 'proto':
-				return is_ssl() ? 'https://' : 'http://';
-
-			case 'menu':
-				_deprecated_argument( 'WP_Admin_Bar', '3.3.0', 'Modify admin bar nodes with WP_Admin_Bar::get_node(), WP_Admin_Bar::add_node(), and WP_Admin_Bar::remove_node(), not the <code>menu</code> property.' );
-				return array(); // Sorry, folks.
-		}
-	}
 
 	/**
 	 * Initializes the admin bar.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55577';
+$wp_version = '6.3-alpha-55580';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.