1. htmlelement api: tabindex

2. htmloptionelement api: index

3. htmloptionscollection api: selectedindex

4. htmlselectelement api: add: index as `before` parameter

5. htmlselectelement api: selectedindex

6. htmltablecellelement api: cellindex

7. htmltablerowelement api: insertcell: `index` parameter can be `-1`

8. htmltablerowelement api: insertcell: `index` parameter is optional

9. htmltablerowelement api: rowindex

10. htmltablerowelement api: sectionrowindex

11. html element: area: tabindex

12. html element: object: tabindex

13. html attribute: tabindex