Fix more PHP 7.4 errors

[staabm]

after this PR 2 errors are left:

1) PHPStan\Analyser\NodeScopeResolverTest::testFile with data set "tests\PHPStan\Analyser\nsrt\range-function.php" ('D:\a\phpstan-src\phpstan-src\...on.php')
Failed assertions in D:\a\phpstan-src\phpstan-src\tests\PHPStan\Analyser\nsrt\range-function.php:

Line 17:
Expected: array{2, 3, 4, 5}
Actual:   array{2.0, 3.0, 4.0, 5.0}

D:\a\phpstan-src\phpstan-src\tests\PHPStan\Analyser\NodeScopeResolverTest.php:320
D:\a\phpstan-src\phpstan-src\tests\vendor\phpunit\phpunit\src\TextUI\Command.php:146

this seems to be a recent regression

---

2) PHPStan\Analyser\NodeScopeResolverTest::testFile with data set "tests\PHPStan\Analyser\nsrt\properties.php" ('D:\a\phpstan-src\phpstan-src\...es.php')
Failed assertions in D:\a\phpstan-src\phpstan-src\tests\PHPStan\Analyser\nsrt\properties.php:

Line 169:
Expected: DOMElement|null
Actual:   string

I wonder why this test does not fail starting with PHP 8.2+ - not sure whether its expected or not

[staabm]

@ondrejmirtes the remaining 2 errors (see PR description) seem to be related to the latest refactorings.

could you double check whether the tests just need to be adjusted or whether the changes introduced a bug?