FIX: j/k place tab focus accordingly so tab will go to the first linked item in the selected post/row

Allow tabbing to continue from the selected post/topic when using the j/k keyboard shortcuts
https://meta.discourse.org/t/when-a-post-is-selected-tab-should-take-you-to-the-first-link/16212
Merge pull request #2815 from cpradio/tab-to-first-link-on-post-when-using-keyboard

FIX: j/k place tab focus accordingly so tab will go to the first linked ...