Chart legends are not focusable

[zac1st1k]

NVD3 version used:
1.8.6

Browser and OS used:
Chrome Mac OS

Live Example:
https://jsfiddle.net/zac1st1k/t8d3n57m/68/

Expected Behaviour:
Line 1 and Line 2 legends can gain focus by pressing TAB key.

Present Behaviour:
Line 1 and Line 2 legends are not keyboard interactive.

Screenshot:

https://bugzilla.mozilla.org/show_bug.cgi?id=1302341

Related doc:
https://allyjs.io/tutorials/focusing-in-svg.html