[perl #68024] [TODO] Make &infix:($op) work

[Tobias Leich via RT]

The design docs indicate that square brackets need to be used, which works with 
rakudo:

constant $foo="+"; say &infix:[$foo](3, 4)
rakudo-moar 4b1df7: OUTPUT«7␤»

So, this is closable with test?