Description:
------------
$this[] outside of class not produces error.

Reproduce code:
---------------
<?php

class foo {
    public function __construct() {
        $this[] = 1;
    }
}

// Fatal error: Cannot re-assign $this
// $this = new foo;

// Fatal error: Using $this when not in object context
// $this->a = new foo;

// Fatal error: Cannot use object of type foo as array
// new foo;

$this[] = new stdClass; // no error

Expected result:
----------------
Fatal error: Using $this when not in object context

Actual result:
--------------
No error