swift234

remove the diag::tuple_global_missing_type diagnostic, which printed as
"a tuple type specifying the type of a global must explicitly state the type of each tuple element".

This diagnostic doesn't make any sense, and is apparently only generated by the old
type checker.  It is also the only thing keeping the "isFirstPass" argument to
TC.validateType() alive, so remove it.

The new type checker does have issues with default values, I filed 
rdar://13946171 to track it, but this old approach (which I wrote, *shame*) 
seems way too broken to salvage.



Swift SVN r5244