Per API review with Ali. While we're here, give the initializer a corresponding 'rawValue' argument label, and change the associated type name to RawValue to match.
Swift SVN r21888
Redefine the RawRepresentable protocol to use an 'init?' method instead of 'fromRaw(Raw)', and a 'raw' get-only property instead of 'toRaw()'. Update the compiler to support deriving conformances for enums and option sets with the new protocol. rdar://problem/18216832
Swift SVN r21762
This makes it so that we actually register the RawOptionSet conformance of imported structs and emit it into executables, fixing <rdar://problem/16295991>.
Swift SVN r16323