AST: Remove SourceFileKind::REPL

include/swift/AST/Module.h

@@ -107,7 +107,6 @@ enum class FileUnitKind {
 enum class SourceFileKind {
   Library,  ///< A normal .swift file.
   Main,     ///< A .swift file that can have top-level code.
-  REPL,     ///< A virtual file that holds the user's input in the REPL.
   SIL,      ///< Came from a .sil file.
   Interface ///< Came from a .swiftinterface file, representing another module.
 };