Bug 244813

Based on https://drafts.csswg.org/css-text-decor-4/#text-decoration-skip-spaces-property (for the explicit use of `text-decoration-skip-spaces: start end`) or on https://drafts.csswg.org/css-text-decor-3/#line-decoration (for the default behavior when no particular property tries to adjust the skipping), spaces at the start and end of the line are supposed to be skipped by text decorations such as underlines.

Safari doesn't do that, as can be seen in https://wpt.fyi/results/css/css-text-decor?sha=249e1eb8e6&label=master&max-count=1&view=subtest&q=css%2Fcss-text-decor%2Ftext-decoration-skip-spaces

The CSSWG has been asked as whether this was a case of the spec being expected to align with implementations, or implementations with the spec, and does seem to expect spec compliance (see https://github.com/w3c/csswg-drafts/issues/4653)