Issue #15017: Properly handle and report network errors on page loads.
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This patch fixes how network errors are handled during page loads: they would not be reported and cause crashes before, and do not anymore.
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#15017 (github issue number if applicable).
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- [X] There are tests for these changes
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Free-standing fonctions parse_html and friends are now static methods
on ServoParser, and the HTML and XML tokenizers have been moved to private
submodules.
