Reject new in class constant initializers to match Zend (#10391)

[PurHur]

Summary

• Restore compile-time rejection of all new expressions in class constant initializers via NewWithoutParensCompileCheck (php-src: Zend/zend_compile.c zend_compile_const_expr()).
• Reverts the incorrect Allow new expressions in class constant initializers (#10198) #10206 allowance; CompilerVersion::supportsClassConstObjectExpressions() now always returns false.
• Updates compliance/unit/AOT guards to expect compile exit 255.

Closes #10391

php-src reference

• Zend/zend_compile.c — class constant new expression validation
• Zend/zend_constants.c — constant object materialization (indirect via global const only)

PHP implementation

• lib/Compiler/NewWithoutParensCompileCheck.php — walks Const_ terminals and rejects nested New_
• lib/CompilerVersion.php — deprecates supportsClassConstObjectExpressions()

Verification

# Issue repro — Zend fatal vs VM compile error (exit 255)
php test/repro/maintainer_gap_new_in_constant.php 2>&1 | tail -1
php bin/vm.php test/repro/maintainer_gap_new_in_constant.php 2>&1 | tail -1

# Maintainer parity script
php test/repro-maintainer/parity_new_without_parens.php

# Targeted PHPUnit
php vendor/bin/phpunit test/unit/NewWithoutParensCompileCheckTest.php
php vendor/bin/phpunit test/compliance/VMTest.php --filter class_const_new

Output (2026-06-22)

# Zend
PHP Fatal error:  New expressions are not supported in this context in .../maintainer_gap_new_in_constant.php on line 8

# VM
parseAndCompile failure: target=.../maintainer_gap_new_in_constant.php: New expressions are not supported in this context

# parity_new_without_parens.php
PASS: class const
PASS: static property
PASS: instance property
ok

# PHPUnit
OK (8 tests, 14 assertions)  # NewWithoutParensCompileCheckTest
OK (4 tests, 4 assertions)   # VMTest --filter class_const_new

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