swift234

Switch archetype assignment for protocols over to the archetype
builder. For this to work, the 'parameter' used to seed the archetype
builder is the 'This' associated type, which implicitly conforms to
the protocol. All other archetype assignments flow from that
archetype.

In the same vein, when faking a polymorphic function type for an
operator found within a protocol, we only need to substitute for the
'This' associated type. The rest are derived due to the implicit
requirement that 'This' conforms to its protocol.

Finally, because archetype assignment within protocols occurs during
type-checking, and that archetype assignment may visit any protocol
visible in the translation unit, we need to validate the types used in
archetype assignment for *all* protocols before attempting archetype
assignment on any one protocol. Thus, perform this type validation
before the main declaration type-checking phase.



Swift SVN r2436