Bug 270347

The following WPT tests regressed with 271357@main, per bisection: * /css/CSS2/css1/c542-letter-sp-001.xht: https://wpt.fyi/results/css/CSS2/css1/c542-letter-sp-001.xht?run_id=5168566772432896&run_id=5070278257803264&diff&filter=ADC * /css/css-text/parsing/letter-spacing-invalid.html: https://wpt.fyi/results/css/css-text/parsing/letter-spacing-invalid.html?run_id=5168566772432896&run_id=5070278257803264&diff&filter=ADC * /css/css-typed-om/the-stylepropertymap/properties/letter-spacing.html: https://wpt.fyi/results/css/css-typed-om/the-stylepropertymap/properties/letter-spacing.html?run_id=5168566772432896&run_id=5070278257803264&diff&filter=ADC * /css/css-values/calc-letter-spacing.html: https://wpt.fyi/results/css/css-values/calc-letter-spacing.html?run_id=5168566772432896&run_id=5070278257803264&diff&filter=ADC * /css/css-values/minmax-length-invalid.html: https://wpt.fyi/results/css/css-values/minmax-length-invalid.html?run_id=5168566772432896&run_id=5070278257803264&diff&filter=ADC To reproduce, in a WPT checkout: ./wpt run --webdriver-binary=path/to/safaridriver --log-mach=- safari /css/CSS2/css1/c542-letter-sp-001.xht /css/css-text/parsing/letter-spacing-invalid.html /css/css-typed-om/the-stylepropertymap/properties/letter-spacing.html /css/css-values/calc-letter-spacing.html /css/css-values/minmax-length-invalid.html Note it appears that the commit in WebKit did _actually_ change many of these WPT tests, but the changes were never exported upstream and thus will be overwritten on the next import. (See e.g. https://github.com/web-platform-tests/wpt/commits/master/css/css-text/parsing/letter-spacing-invalid.html which hasn't had any commits in the past six years.)