[mono-vb] Support for the ternary if construct

[CFP]

Hello everyone,

Many of my projects written in VB.Net could be built using mono, save the
fact that the ternary construct `If(Condition, TrueCase, FalseCase)` isn't
supported yet. Is there a way to help with the implementation of this
construct, or is someone already working on this? Sadly my knowledge of the
mono vb compiler is close to nothing, and yet I'd really be willing to see
mono support this.

Of course, switching my ternary ifs to plain ifs is possible, but there are
an approximate 60 of those in my code...

Thanks!
CFP.