Left/right/home/end only work if a row is focused, in case a textfiel…

…d has focus

Different approach -- use tab/shift+tab to move between cells in the …

…currently focused row

Try putting readonly just on parent

Use aria-readonly on gridcells so that they aren't incessantly report…

…ed as readonly

Note that Canary is currently required

Update aria-owns recommendation info

Remove unnecessary option