swift234

fix <rdar://problem/23942743> [QoI] Bad diagnostic when errors inside enum constructor

On something like this:
  let x = .Tomato(cloud: .None)

we previously emitted a "type of expression is ambiguous without more context" error
while pointing to .None.  With a previous fix, we now produce the same error pointing
to the .Tomato.  With this fix, we now produce:

error: reference to member 'Tomato' cannot be resolved without a contextual type

to really drive the problem home.