fix: Do not remove table top border with thead and bottom border with tfoot at page break

[MurakamiShinyu]

When a table with border-collapse: collapse style is split across pages, the top border of the table should not be removed if the table has thead and the bottom border should not be removed if the table has tfoot.

CSS Table Module Level 3 §6.2. Repeating headers across pages says:

When the header rows are being repeated, user agents must leave room and if needed render the table top border. The same applies for footer rows and the table bottom border.

[MurakamiShinyu]

Test sample:
https://gist.githubusercontent.com/MurakamiShinyu/58d7a59dafad3901c5769dfdf2d2feb7/raw/table-border-collapse-thead-tfoot.html

Test with Vivliostyle Viewer:

• Before this fix (v2.31.0): https://vivliostyle.github.io/viewer/v2.31.0/#src=https://gist.githubusercontent.com/MurakamiShinyu/58d7a59dafad3901c5769dfdf2d2feb7/raw/table-border-collapse-thead-tfoot.html
• After this fix: https://vivliostyle-git-fix-table-border-break-vivliostyle.vercel.app/#src=https://gist.githubusercontent.com/MurakamiShinyu/58d7a59dafad3901c5769dfdf2d2feb7/raw/table-border-collapse-thead-tfoot.html

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
vivliostyle	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Feb 28, 2025 4:54pm