MDL-60281 general: remove class object() completely

This class was deprecated under MDL-52471 and was showing debugging notice from Moodle 3.0.1
In PHP7.2 the class declaration fails with fatal error even if it's not used anywhere

lib/setuplib.php

@@ -51,27 +51,6 @@ define('MEMORY_EXTRA', -3);
 /** Extremely large memory limit - not recommended for standard scripts */
 define('MEMORY_HUGE', -4);
 
-
-/**
- * Simple class. It is usually used instead of stdClass because it looks
- * more familiar to Java developers ;-) Do not use for type checking of
- * function parameters. Please use stdClass instead.
- *
- * @package    core
- * @subpackage lib
- * @copyright  2009 Petr Skoda  {@link http://skodak.org}
- * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
- * @deprecated since 2.0
- */
-class object extends stdClass {
-    /**
-     * Constructor.
-     */
-    public function __construct() {
-        debugging("'object' class has been deprecated, please use stdClass instead.", DEBUG_DEVELOPER);
-    }
-};
-
 /**
  * Base Moodle Exception class
  *

lib/tests/setuplib_test.php

@@ -469,12 +469,6 @@ class core_setuplib_testcase extends advanced_testcase {
         }
     }
 
-    public function test_object() {
-        $obj = new object();
-        $this->assertDebuggingCalled("'object' class has been deprecated, please use stdClass instead.");
-        $this->assertInstanceOf('stdClass', $obj);
-    }
-
     /**
      * Data provider for test_get_real_size().
      *