Drop DOM dependency

[staabm]

requires theseer/tokenizer#38

before this PR (using PHPUnit 12.4.4)

➜  slow-coverage-xml1 git:(main) ✗ hyperfine 'php coverage-xml.php'           
Benchmark 1: php coverage-xml.php
  Time (mean ± σ):     11.772 s ±  0.550 s    [User: 10.209 s, System: 1.237 s]
  Range (min … max):   11.008 s … 12.568 s    10 runs

after this PR:

➜  slow-coverage-xml1 git:(main) ✗ hyperfine 'php coverage-xml.php'
Benchmark 1: php coverage-xml.php
  Time (mean ± σ):      5.999 s ±  0.385 s    [User: 5.008 s, System: 0.789 s]
  Range (min … max):    5.647 s …  6.732 s    10 runs

---

env

php -v
PHP 8.3.28 (cli) (built: Nov 18 2025 22:17:16) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.28, Copyright (c) Zend Technologies

[staabm]

double check against phpstan-src@05b80ef861 on my macos m4 pro laptop

before this PR (using PHPUnit 12.4.4)

Generating code coverage report in PHPUnit XML format ... done [00:31.317]

after this PR

Generating code coverage report in PHPUnit XML format ... done [00:17.598]