swift234

Revert "Centralize the logic for synthesized conformances."

It causes some fails in compiler_crashers:

    Swift :: compiler_crashers/0986-swift-unboundgenerictype-get.swift
    Swift :: compiler_crashers/1103-swift-unboundgenerictype-get.swift
    Swift :: compiler_crashers/1223-swift-lexer-leximpl.swift
    Swift :: compiler_crashers/1276-swift-metatypetype-get.swift
    Swift :: compiler_crashers/1287-swift-printingdiagnosticconsumer-handlediagnostic.swift



Swift SVN r26136