[php-src] Issue #21072: zend_ast assertion failure in class property initializer

Issue: https://github.com/php/php-src/issues/21072
Author: vi3tL0u1s

### Description

The following code:

```php
<?php 
class C { public $p = (unset)C::class; }
new C;
```

Resulted in this output:
```
php: /path/to/php-src/Zend/zend_ast.c:817: zend_ast_evaluate_inner: Assertion `0' failed.
Aborted
```

Commit:
```
4d5b651e9003ece86b4146a0d1d12417a07eb3a3
```

Build configuration:
```
CC="clang" CXX="clang++" CFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" CXXFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" ./configure --enable-debug --enable-address-sanitizer --disable-all --enable-cli
```


### PHP Version

```plain
PHP 8.6.0-dev (cli) (built: Jan 29 2026 14:13:52) (NTS DEBUG)
Copyright (c) The PHP Group
Zend Engine v4.6.0-dev, Copyright (c) Zend Technologies
    with Zend OPcache v8.6.0-dev, Copyright (c), by Zend Technologies
```

### Operating System

Ubuntu 22.04